This work was supported by the National Science Foundation, through the Nebraska MRSEC (Grant DMR-1420645), CHE-1565692, and CHE-145533 as well as the Nebraska Center for Energy Science Research.

CAUTION: Please consult the lab&#8217;s material safety data sheets (MSDS) before proceeding. The chemicals used in these synthesis protocols have associated health hazards. Additionally, nanomaterials have additional hazards compared to their bulk counterpart. Please use all appropriate safety practices when performing a nanocrystal reaction including the use of a fume hood or glovebox and the proper personal protective equipment (safety glasses, gloves, lab coat, pants, closed-toe shoes, etc.).
1. Precursor Synthesis
<ol>
	<li>Cesium oleate precursor synthesis 
	NOTE: Cesium oleate is synthesized under a N2 environment.
	<ol>
		<li>Add 0.203 g of cesium carbonate (Cs2CO3), 10 mL of octadecene (ODE), and 1.025 mL of oleic acid (OA) to a three necked round bottom stirring flask. The three necked round bottom flask for cesium oleate precursor is labeled 1 in Figure 1a.</li>
		<li>Place a thermometer or thermocouple into one of the necks via a rubber stopper.</li>
		<li>Place a rubber septum into one of the remaining necks and then attach the third and final neck to a nitrogen gas line via a Schlenk line. Place the mixture under a gaseous nitrogen atmosphere.</li>
		<li>Heat the mixture to 150 &#176;C with constant stirring at a stirring speed of 399 mm/s using a 2.54 cm magnetic stir bar until the Cs2CO3 fully dissolves.</li>
		<li>Lower the temperature to 100 &#176;C to avoid precipitation and decomposition of the cesium oleate and leave stirring at the same stirring speed as in step 1.1.4.</li>
	</ol>
	</li>
	<li>Oleylamine-PbBr2 precursor synthesis 
	NOTE: Oleylamine-PbBr2 precursor is synthesized under a N2 environment.
	<ol>
		<li>Add 37.5 mL of ODE, 7.5 mL of oleylamine (OAm), 3.75 mL of OA, and 1.35 mmol of PbBr2 into another three necked round bottom stirring flask. The three necked round bottom stirring flask for OAm-PbBr2 is labeled 2 in Figure 1a. Figure 1b shows the unmixed precursor solution.</li>
		<li>Place a thermometer or thermocouple into one of the necks and place some sort of polymer film around thermometer/thermocouple to seal neck, see Figure 1.</li>
		<li>Place a rubber stopper in one of the remaining necks and then attach the third and final neck to a nitrogen gas line via a Schlenk line. Place mixture under gaseous nitrogen atmosphere.</li>
		<li>Heat the mixture to 100 &#176;C with constant stirring at a stirring speed of 599 mm/s using a magnetic stir bar until the PbBr2 is fully dissolved. The precursor solution under constant stirring is shown in Figure 1c and the fully dissolved precursor solution is shown in Figure 1d.</li>
		<li>Heat the mixture to 170 &#176;C with constant stirring, notice the mixture undergoes a color change to dark yellow once reaching 170 &#176;C as seen in Figure 1d. Leave stirring under 170 &#176;C heat.</li>
	</ol>
	</li>
</ol>
2. CsPbBr3 Quantum Dot Synthesis
<ol>
	<li>Using a 2 mL glass syringe, with a 10 cm long 18 gauge needle, extract 1.375 mL of cesium oleate precursor from three neck flask through the rubber septum as shown in Figure 2a.</li>
	<li>Quickly inject, via the rubber septum, the 1.375 mL of cesium oleate precursor into the three neck flask containing the OAm-PbBr2 precursor, as shown in Figure 2b. There should be an observable color change, a brilliant yellow-green, as shown in Figure 2c.</li>
	<li>After injecting the cesium oleate precursor, wait 5 s, remove the three neck flask from the heat, and immerse the three-neck round bottom flask into an ice/water bath at 0 &#176;C, as shown in Figure 3a.</li>
	<li>Separate the solution in the three neck flask equally into 2 test tubes, roughly 25 mL per test tube.</li>
	<li>Add 25mL of acetone to each supernatant solutions, then separate with centrifuge using parameters below.</li>
	<li>Separate the quantum dots using a centrifuge at 2431.65 x g for 5 min at room temperature setting, as shown in Figure 3b.</li>
	<li>Separate the supernatant and centrifuged quantum dots, as shown in Figure 3c, by pouring the supernatant into an empty test tube.</li>
	<li>Finally, dissolve the separated quantum dots in 10-25 mL of hexanes or cyclohexanes. This solution can then be used as an ink in the inkjet printer cartridges for printing thin films. 
	NOTE: A commercially available inkjet printer was used to print all the quantum dot thin films of the inorganic halide-based perovskite inks. In this protocol substrates of amorphous glass and Indium tin oxide coated polyethylene terephthalate (ITO/PET) were used during measurements. To ensure that the substrate surface is clean before printing, the substrates were cleaned using an acetone wash followed by a methanol wash.</li>
</ol>
3. Cleaning the Printer Head
<ol>
	<li>First make sure the printer is plugged in and the power turned on to gain access to the ink cartridges and printer head.</li>
	<li>Remove the ink cartridges from the printer head, open the top of the printer and wait for the ink cartridges to return to the center position and the red lights underneath the ink cartridges to be illuminated, and then remove all cartridges.</li>
	<li>Move the print head slightly to the right and pull out the guard on the ink tray so that it allows the tray to stay in place as shown in Figure 4. Reach to the back of the ink tray and pinch the plastic divider separating the two halves of the print head. Pull gently and the print head will be easily removed.</li>
	<li>To clean the print head, prepare a dish with a few millimeters of warm water. Place the print head in the water with the slits at the bottom submerged. Avoid contact between the green electronic parts on the back and the water because this has the potential to do damage to the print head.</li>
	<li>Use a pipette and warm water to drop water on the resistors. Leave the print head sitting in warm water for 1-2 h.</li>
	<li>Once finished soaking in warm water, place the printer head on a lab tissue and leave to dry at least 20 min. Avoid wiping the bottom of the print head because the fibers from the wipe can get stuck in the slits where ink is dispensed.</li>
	<li>Return the print head to its position and push the guard back to its original position.</li>
</ol>
4. Printing Perovskite Quantum Dot Inks
NOTE: This protocol uses an inkjet printer that includes the ability to print CD labels onto CDs with the aid of a rigid CD disc tray. It is recommended before printing perovskites, that one cut out a preferred shape and size of the substrate and then print the exact size and shape of the desired substrate on the CD disk itself using black ink, as shown in Figure 5.
<ol>
	<li>Draw a straight line at the edge of the disk and continue it onto the CD disc tray. This way, the CD template can be lined up the same way every time and ensure the inks print in the desired location.</li>
	<li>Place the substrate over the ink images printed on the disk. The substrate can be held in place using double sided tape or some other adhesive, as shown in Figure 5b.</li>
	<li>Before filling the ink cartridges, ensure the orange cover is installed correctly on the bottom of the ink cartridge, as shown in Figure 6a. This will prevent ink from spilling out the bottom of the cartridge.</li>
	<li>Once the ink solution is made, as in step 2.9, and the cover is on the cartridge, use a pipette to inject the quantum dot ink into the top of the ink cartridge, as shown in Figure 6a. 
	NOTE: The quantum dot ink will be absorbed by the sponge until it becomes saturated and the remaining ink will be stored in the compartment beside the sponge. Avoid over-filling this compartment, because ink can escape from the top when it becomes nearly full.</li>
	<li>Once the cartridge is filled to the desired amount, plug the top with the rubber stopper and carefully remove the orange bottom cover. Be prepared for a little ink to escape through the bottom when performing this action.</li>
	<li>Place the ink cartridge in the printer head and be sure it snaps into place, as shown in Figure 6b, be sure to insert the remaining cartridges, either empty or full before continuing to next step, as shown in Figure 6c.</li>
	<li>Close up the printer and wait for the printer head to return to the far right-hand side of the printer.</li>
	<li>Make sure the color of the images being printed corresponds to the ink cartridge color containing the quantum dots. A solid image of cyan, magenta, or yellow have been found to work best (black is tricky because there are two black cartridges).</li>
	<li>Click print at the bottom right-hand corner and follow the on-screen instructions.</li>
	<li>While the printer is warming up, check that the disk is properly aligned on the disk tray, such that the image on the screen will print exactly where expected.</li>
	<li>An instruction will appear on the screen that directs the user to open the disk cover on the printer and insert the disk tray containing the disk into the machine. Perform this action and then press the resume (orange blinking) button on the printer or click the &#8220;OK&#8221; button on the screen, as shown in Figure&#160;7a and 7b.</li>
	<li>At this point the printer will accept the disk tray and print perovskites on the substrate, after printing is complete; check that the inks actually printed onto the substrate as clogging is a common problem.
	<ol>
		<li>Hold an ultra violet (UV) lamp over the substrate, if the printing did not work there will be something similar to Figure 7c; otherwise there will be luminescing film as in Figure 7d if the above protocol worked properly.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Weber, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CH3NH3PbX3,+ein+Pb(II)-System+mit+kubischer+Perowskitstruktur+/+CH3NH3PbX3,+a+Pb(II)-System+with+Cubic+Perovskite+Structure.">CH3NH3PbX3, ein Pb(II)-System mit kubischer Perowskitstruktur / CH3NH3PbX3, a Pb(II)-System with Cubic Perovskite Structure.</a> Zeitschrift f&#252;r Naturforschung B. 33, 1443-1445 (1978).</li><li>Weber, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=(+x+=+0-3+),+ein+Sn+(+II+)+-System+mit+kubischer+Perowskitstruktur.">( x = 0-3 ), ein Sn ( II ) -System mit kubischer Perowskitstruktur.</a> Zeitschrift f&#252;r Naturforschung B. 33, 862-865 (1978).</li><li>Kojima, A., Teshima, K., Shirai, Y., Miyasaka, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organometal+Halide+Perovskites+as+Visible-Light+Sensitizers+for+Photovoltaic+Cells.">Organometal Halide Perovskites as Visible-Light Sensitizers for Photovoltaic Cells.</a> Journal of the American Chemical Society. 131, 6050-6051 (2009).</li><li>. National Renewable Energy Laboratory NREL Best Research-Cell Efficiencies Available from: <a target="_blank" href="https://www.nrel.gov/pv/assets/images/efficiency-chart.png">https://www.nrel.gov/pv/assets/images/efficiency-chart.png</a> (2018)</li><li>Chen, Z., Wang, J. J., Ren, Y., Yu, C., Shum, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Schottky+solar+cells+based+on+CsSnI+3+thin-films.">Schottky solar cells based on CsSnI 3 thin-films.</a> Applied Physics Letters. 101 (9), 93901 (2012).</li><li>Sanehira, E. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhanced+mobility+CsPbI+3+quantum+dot+arrays+for+record-efficiency,+high-voltage+photovoltaic+cells.">Enhanced mobility CsPbI 3 quantum dot arrays for record-efficiency, high-voltage photovoltaic cells.</a> Science Advances. 3 (10), 4204 (2017).</li><li>Jia, Y., Kerner, R. A., Grede, A. J., Rand, B. P., Giebink, N. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous-wave+lasing+in+an+organic-inorganic+lead+halide+perovskite+semiconductor.">Continuous-wave lasing in an organic-inorganic lead halide perovskite semiconductor.</a> Nature Photonics. 11 (12), 784-788 (2017).</li><li>Eaton, S. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lasing+in+robust+cesium+lead+halide+perovskite+nanowires.">Lasing in robust cesium lead halide perovskite nanowires.</a> Proceedings of the National Academy of Sciences. 113 (8), 1993 (2016).</li><li>Yakunin, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Low-threshold+amplified+spontaneous+emission+and+lasing+from+colloidal+nanocrystals+of+caesium+lead+halide+perovskites.">Low-threshold amplified spontaneous emission and lasing from colloidal nanocrystals of caesium lead halide perovskites.</a> Nature Communications. 6, 1-8 (2015).</li><li>Fu, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Broad+Wavelength+Tunable+Robust+Lasing+from+Single-Crystal+Nanowires+of+Cesium+Lead+Halide+Perovskites+(CsPbX3,+X+=+Cl,+Br,+I).">Broad Wavelength Tunable Robust Lasing from Single-Crystal Nanowires of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, I).</a> ACS Nano. 10 (8), 7963-7972 (2016).</li><li>Jeong, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=All-Inorganic+CsPbI+3+Perovskite+Phase-Stabilized+by+Poly(ethylene+oxide)+for+Red-Light-Emitting+Diodes.">All-Inorganic CsPbI 3 Perovskite Phase-Stabilized by Poly(ethylene oxide) for Red-Light-Emitting Diodes.</a> Advanced Functional Materials. , 1706401 (2018).</li><li>Pan, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bidentate+Ligand-Passivated+CsPbI3Perovskite+Nanocrystals+for+Stable+Near-Unity+Photoluminescence+Quantum+Yield+and+Efficient+Red+Light-Emitting+Diodes.">Bidentate Ligand-Passivated CsPbI3Perovskite Nanocrystals for Stable Near-Unity Photoluminescence Quantum Yield and Efficient Red Light-Emitting Diodes.</a> Journal of the American Chemical Society. 140 (2), 562-565 (2018).</li><li>Xiao, Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficient+perovskite+light-emitting+diodes+featuring+nanometre-sized+crystallites.">Efficient perovskite light-emitting diodes featuring nanometre-sized crystallites.</a> Nature Photonics. 11 (2), 108-115 (2017).</li><li>Stoumpos, C. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Crystal+growth+of+the+perovskite+semiconductor+CsPbBr3:+A+new+material+for+high-energy+radiation+detection.">Crystal growth of the perovskite semiconductor CsPbBr3: A new material for high-energy radiation detection.</a> Crystal Growth and Design. 13 (7), 2722-2727 (2013).</li><li>Ilie, C. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inkjet+printable-photoactive+all+inorganic+perovskite+films+with+long+effective+photocarrier+lifetimes.">Inkjet printable-photoactive all inorganic perovskite films with long effective photocarrier lifetimes.</a> Journal of Physics Condensed Matter. 30 (18), (2018).</li><li>Shoaib, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Directional+Growth+of+Ultralong+CsPbBr3Perovskite+Nanowires+for+High-Performance+Photodetectors.">Directional Growth of Ultralong CsPbBr3Perovskite Nanowires for High-Performance Photodetectors.</a> Journal of the American Chemical Society. 139 (44), 15592-15595 (2017).</li><li>Swarnkar, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantum+dot-induced+phase+stabilization+of+a-CsPbI3+perovskite+for+high-efficiency+photovoltaics.">Quantum dot-induced phase stabilization of a-CsPbI3 perovskite for high-efficiency photovoltaics.</a> Science. 354 (6308), 92-96 (2016).</li><li>Kumar, M. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lead-free+halide+perovskite+solar+cells+with+high+photocurrents+realized+through+vacancy+modulation.">Lead-free halide perovskite solar cells with high photocurrents realized through vacancy modulation.</a> Advanced Materials. 26 (41), 7122-7127 (2014).</li><li>Burschka, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sequential+deposition+as+a+route+to+high-performance+perovskite-sensitized+solar+cells.">Sequential deposition as a route to high-performance perovskite-sensitized solar cells.</a> Nature. 499 (7458), 316-319 (2013).</li><li>Dirin, D. N., Cherniukh, I., Yakunin, S., Shynkarenko, Y., Kovalenko, M. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Solution-Grown+CsPbBr+3+Perovskite+Single+Crystals+for+Photon+Detection.">Solution-Grown CsPbBr 3 Perovskite Single Crystals for Photon Detection.</a> Chemistry of Materials. 28 (23), 8470-8474 (2016).</li><li>Zhou, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vapor+Growth+and+Tunable+Lasing+of+Band+Gap+Engineered+Cesium+Lead+Halide+Perovskite+Micro/Nanorods+with+Triangular+Cross+Section.">Vapor Growth and Tunable Lasing of Band Gap Engineered Cesium Lead Halide Perovskite Micro/Nanorods with Triangular Cross Section.</a> ACS Nano. 11 (2), 1189-1195 (2017).</li><li>Teng, K. F., Vest, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+Ink+Jet+Technology+on+Photovoltaic+Metallization.">Application of Ink Jet Technology on Photovoltaic Metallization.</a> IEEE Electron Device Letters. 9 (11), 591-593 (1988).</li><li>Habas, S. E., Platt, H. a. S., van Hest, M. F. A. M., Ginley, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Low-Cost+Inorganic+Solar+Cells:+From+Ink+To+Printed+Device.">Low-Cost Inorganic Solar Cells: From Ink To Printed Device.</a> Chemical Reviews. 110 (11), 6571-6594 (2010).</li><li>Leenen, M. A. M., Arning, V., Thiem, H., Steiger, J., Anselmann, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Printable+electronics:+Flexibility+for+the+future.">Printable electronics: Flexibility for the future.</a> Physica Status Solidi (A) Applications and Materials Science. 206 (4), 588-597 (2009).</li><li>Koolyk, M., Amgar, D., Aharon, S., Etgar, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kinetics+of+cesium+lead+halide+perovskite+nanoparticle+growth;+focusing+and+de-focusing+of+size+distribution.">Kinetics of cesium lead halide perovskite nanoparticle growth; focusing and de-focusing of size distribution.</a> Nanoscale. 8 (12), 6403-6409 (2016).</li><li>Palazon, F., Di Stasio, F., Lauciello, S., Krahne, R., Prato, M., Manna, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+of+CsPbBr+3+nanocrystals+upon+post-synthesis+annealing+under+an+inert+atmosphere.">Evolution of CsPbBr 3 nanocrystals upon post-synthesis annealing under an inert atmosphere.</a> Journal of Materials Chemistry C. 4 (39), 9179-9182 (2016).</li><li>Scherrer, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bestimmung+der+Gr&#246;&#223;e+und+der+inneren+Struktur+von+Kolloidteilchen+mittels+R&#246;ntgenstrahlen.+Nachrichten+von+der+Gesellschaft+der+Wissenschaften+zu+G&#246;ttingen.">Bestimmung der Gr&#246;&#223;e und der inneren Struktur von Kolloidteilchen mittels R&#246;ntgenstrahlen. Nachrichten von der Gesellschaft der Wissenschaften zu G&#246;ttingen.</a> Nachrichten von der Gesellschaft der Wissenschaften zu G&#246;ttingen, Mathematisch-Physikalische Klasse. 2, 98-100 (1918).</li><li>Shekhirev, M., Goza, J., Teeter, J., Lipatov, A., Sinitiskii, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+Cesium+Lead+Halide+Quantum+Dots.">Synthesis of Cesium Lead Halide Quantum Dots.</a> Journal of Chemical Education. 94 (8), 1150-1156 (2017).</li></ol>

The authors have no financial conflicts of interest and have nothing to disclose.

There are many parameters involved in the inkjet printing process that affect the final printed film. The discussion of all those parameters is beyond the scope of this protocol, but as this protocol focuses on a solution-based synthesis and deposition method, it is appropriate to give a short comparison to other well-known solution-based deposition methods: the spin-coating method and the doctor-blade method.
The spin-coating method is very fast, produces uniform films, and is low cost. The f...

Dieter Weber synthesized the first organic-inorganic hybrid&#160;halide&#160;perovskites in 19781,2. Roughly 30 years later in 2009, Akihiro Kojima and collaborators fabricated photovoltaic devices using the same organic-inorganic hybrid&#160;halide&#160;perovskites synthesized by Weber, namely, CH3NH3PbI3 and CH3NH3PbBr33. These experiments were the beginning of a subsequent tidal wave of research focusing on the photovoltaic properties of organic-inorganic hybrid halide perovskites. From 2009 to 2018, the device power conversion efficiency dramatically increased from 3.8%3 to over 23%4, making organic-inorganic hybrid&#160;halide perovskites comparable to Si-based solar cells. As with the organic-inorganic halide-based perovskites, the inorganic halide-based perovskites started gaining traction in the research community around 2012 when the first photovoltaic device efficiency was measured to be 0.9%5. Since 2012 the all inorganic halide-based perovskites have come a long way with some device efficiencies measured to be over 13% as in the 2017 study by Sanehira et al.6&#160;Both the organic-based and inorganic-based perovskites find applications related to lasers7,8,9,10, light emitting diodes11,12,13, high energy radiation detection14, photo detection15,16, and of course photovoltaic applications5,15,17,18. Over almost the past decade, many different synthesis techniques have emerged from scientists and engineers ranging from solution processed methods to vacuum vapor deposition techniques19,20,21. The halide&#160;perovskites synthesized using a solution-processed method are advantageous as they can easily be employed as inks for inkjet printing15.
In 1987, the first reported use of inkjet printing of solar cells was presented. Since then, scientists and engineers have sought ways to successfully print all inorganic solar cells with attractive performance properties and low implementation costs22. There are many advantages to inkjet printing solar cells, as compared to some of the common vacuum based fabrication methods. An important aspect of the inkjet printing method is that solution-based materials are used as inks. This opens the door for trials of many different materials, such as inorganic&#160;perovskite-based inks, which can be synthesized by facile wet chemical methods. In other words, inkjet printing of solar cell materials is a low-cost route to rapid prototyping. Inkjet printing also has the advantages of being able to print large areas on flexible substrates and print by design at low temperatures in atmospheric conditions. Furthermore, inkjet printing is highly suitable for mass production allowing for realistic low cost roll-to-roll implementation23,24.
In this article, we first discuss the steps involved with synthesizing inorganic&#160;perovskite quantum dot inks for inkjet printing. Then, we describe the additional steps for preparing inks for printing and the actual procedures for inkjet printing a photoactive film using a commercially available inkjet printer. Finally, we discuss the characterization of the printed films which is necessary to ensure the films are of proper chemical and crystal composition for high quality device performance.

<table><tbody><tr><td>Oleic acid, 90%</td><td>Sigma Aldrich</td><td>364525</td><td>Technical grade</td></tr><tr><td>Oleylamine, 70%</td><td>Sigma Aldrich</td><td>O7805</td><td>Technical grade</td></tr><tr><td>1-octadecene, 90%</td><td>Sigma Aldrich</td><td>O806</td><td>Technical grade</td></tr><tr><td>Acetone, &gt;95%</td><td>Fisher</td><td>67641</td><td>Certified ACS</td></tr><tr><td>Cesium Carbonate, 99%</td><td>Chem-Impex</td><td>1955</td><td>Assay</td></tr><tr><td>Hexane, 98.5%</td><td>Sigma Aldrich</td><td>178918</td><td>Mixture of isomers</td></tr><tr><td>Cyclohexane, 99.9%</td><td>Sigma Aldrich</td><td>110827</td><td></td></tr><tr><td>Lead(II) bromide, 98%</td><td>Sigma Aldrich</td><td>211141</td><td></td></tr><tr><td>Lead(II) iodide, 99%</td><td>Sigma Aldrich</td><td>211168</td><td></td></tr></tbody></table>

inkjet printing all inorganic halide perovskite inks for photovoltaic applications

A method for synthesizing photoactive inorganic&#160;perovskite quantum dot inks and an inkjet printer deposition method, using the synthesized inks, are demonstrated. The ink synthesis is based on a simple wet chemical reaction and the inkjet printing protocol is a facile step by step method. The inkjet printed thin films have been characterized by X-ray diffraction, optical absorption spectroscopy, photoluminescent spectroscopy, and electronic transport measurements. X-ray diffraction of the printed quantum dot films indicates a crystal structure consistent with an orthorhombic room temperature phase with (001) orientation. In conjunction with other characterization methods, the X-ray diffraction&#160;measurements show high quality films can be obtained through the inkjet printing method.

Crystal Structure Characterization
Characterizing the crystal structure is vital regarding the synthesis of the inorganic&#160;perovskites. X-ray diffraction (XRD) was performed in air at room temperature on a diffractometer using a 1.54 &#197; wavelength Cu-K&#945; light source. Using the above protocols should lead to a room temperature orthorhombic crystal structure for the CsPbBr3 quantum dot inks as shown...

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Inkjet Printing All Inorganic Halide Perovskite Inks for Photovoltaic Applications

A protocol for synthesizing inorganic-lead-halide hybrid perovskite quantum dot inks for inkjet printing and the protocol for preparing and printing the quantum dot inks in an inkjet printer with post characterization techniques are presented.

A method for synthesizing photoactive inorganic&#160;perovskite quantum dot inks and an inkjet printer deposition method, using the synthesized inks, are ...

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Research

JoVE Journal

Chemistry

11.0K Views.  State University of New York-Oswego. De belangrijkste voordelen van deze techniek zijn dat het zeer geschikt is voor grote gebiedsdepositie, rapid prototyping en print by design, wat een hoog potentieel voor roll-to-roll productie suggereert. Hoewel dit systeem inzicht kan geven in anorganische fotovoltaïsche stoffen, kan het ook worden toegepast op andere systemen zoals organische fotovoltaïsche of biofysica. Het aantonen van de chemische synthese procedure zal Mason McCormick, een undergraduate van de Sinitsky laboratorium.

Video: Inkjet Printing All Inorganic Halide Perovskite Inks for Photovoltaic Applications

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices have used devices prepared by spin coating, a process that is not amenable to large-scale fabrication. This mismatch in device fabrication makes it difficult to translate quantitative results obtained in the laboratory to the commercial level, making optimization difficult. Using a mini-slot die coater, this mismatch can be resolved by translating the commercial process to the laboratory and characterizing the structure formation in the active layer of the device in real time and in situ as films are coated onto a substrate. The evolution of the morphology was characterized under different conditions, allowing us to propose a mechanism by which the structures form and grow. This mini-slot die coater offers a simple, convenient, material efficient route by which the morphology in the active layer can be optimized under industrially relevant conditions. The goal of this protocol is to show experimental details of how a solar cell device is fabricated using a mini-slot die coater and technical details of running in situ structure characterization using the mini-slot die coater.

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Here, we present a protocol to fabricate organic thin film solar cells using a mini-slot die coater and related in-line structure characterizations using synchrotron scattering techniques.

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices ...

Engineering

Digital Printing of Titanium Dioxide for Dye Sensitized Solar Cells

Silicon solar cell manufacturing is an expensive and high energy consuming process. In contrast, dye sensitized solar cell production is less environmentally damaging with lower processing temperatures presenting a viable and low cost alternative to conventional production. This paper further enhances these environmental credentials by evaluating the digital printing and therefore additive production route for these cells. This is achieved here by investigating the formation and performance of a metal oxide photoelectrode using nanoparticle sized titanium dioxide. An ink-jettable material was formulated, characterized and printed with a piezoelectric inkjet head to produce a 2.6 &#181;m thick layer. The resultant printed layer was fabricated into a functioning cell with an active area of 0.25 cm2 and a power conversion efficiency of 3.5%. The binder-free formulation resulted in a reduced processing temperature of 250 &#176;C, compatible with flexible polyamide substrates which are stable up to temperatures of 350 &#730;C. The authors are continuing to develop this process route by investigating inkjet printing of other layers within dye sensitized solar cells.

This paper investigates the suitability of inkjet printing for the manufacturing of dye-sensitized solar cells. A binder-free TiO2 nanoparticle ink was formulated and printed onto a FTO glass substrate. The printed layer was fabricated into a cell with an active area of 0.25 cm2 and an efficiency of 3.5%.

Silicon solar cell manufacturing is an expensive and high energy consuming process. In contrast, dye sensitized solar cell production is less ...

Fabrication of Fully Solution Processed Inorganic Nanocrystal Photovoltaic Devices

We demonstrate a method for the preparation of fully solution processed inorganic solar cells from a spin and spray coating deposition of nanocrystal inks. For the photoactive absorber layer, colloidal CdTe and CdSe nanocrystals (3-5 nm) are synthesized using an inert hot injection technique and cleaned with precipitations to remove excess starting reagents. Similarly, gold nanocrystals (3-5 nm) are synthesized under ambient conditions and dissolved in organic solvents. In addition, precursor solutions for transparent conductive indium tin oxide (ITO) films are prepared from solutions of indium and tin salts paired with a reactive oxidizer. Layer-by-layer, these solutions are deposited onto a glass substrate following annealing (200-400 &#176;C) to build the nanocrystal solar cell (glass/ITO/CdSe/CdTe/Au). Pre-annealing ligand exchange is required for CdSe and CdTe nanocrystals where films are dipped in NH4Cl:methanol to replace long-chain native ligands with small inorganic Cl- anions. NH4Cl(s) was found to act as a catalyst for the sintering reaction (as a non-toxic alternative to the conventional CdCl2(s) treatment) leading to grain growth (136&#177;39 nm) during heating. The thickness and roughness of the prepared films are characterized with SEM and optical profilometry. FTIR is used to determine the degree of ligand exchange prior to sintering, and XRD is used to verify the crystallinity and phase of each material. UV/Vis spectra show high visible light transmission through the ITO layer and a red shift in the absorbance of the cadmium chalcogenide nanocrystals after thermal annealing. Current-voltage curves of completed devices are measured under simulated one sun illumination. Small differences in deposition techniques and reagents employed during ligand exchange have been shown to have a profound influence on the device properties. Here, we examine the effects of chemical (sintering and ligand exchange agents) and physical treatments (solution concentration, spray-pressure, annealing time and annealing temperature) on photovoltaic device performance.

This protocol describes the synthesis and solution deposition of inorganic nanocrystals layer by layer to produce thin film electronics on non-conductive surfaces. Solvent-stabilized inks can produce complete photovoltaic devices on glass substrates via spin and spray coating following post-deposition ligand exchange and sintering.

We demonstrate a method for the preparation of fully solution processed inorganic solar cells from a spin and spray coating deposition of nanocrystal ...

Influence of Hybrid Perovskite Fabrication Methods on Film Formation, Electronic Structure, and Solar Cell Performance

Hybrid organic/inorganic halide perovskites have lately been a topic of great interest in the field of solar cell applications, with the potential to achieve device efficiencies exceeding other thin film device technologies. Yet, large variations in device efficiency and basic physical properties are reported. This is due to unintentional variations during film processing, which have not been sufficiently investigated so far. We therefore conducted an extensive study of the morphology and electronic structure of a large number of CH3NH3PbI3 perovskite where we show how the preparation method as well as the mixing ratio of educts methylammonium iodide and lead(II) iodide impact properties like film formation, crystal structure, density of states, energy levels, and ultimately the solar cell performance.

We present an extensive study on the effects of different fabrication methods for organic/inorganic perovskite thin films by comparing crystal structures, density of states, energy levels, and ultimately the solar cell performance.

Hybrid organic/inorganic halide perovskites have lately been a topic of great interest in the field of solar cell applications, with the potential to ...

Morphology Control for Fully Printable Organic&#8211;Inorganic Bulk-heterojunction Solar Cells Based on a Ti-alkoxide and Semiconducting Polymer

The photoactive layer of a typical organic thin-film bulk-heterojunction (BHJ) solar cell commonly uses fullerene derivatives as the electron-accepting material. However, fullerene derivatives are air-sensitive; therefore, air-stable material is needed as an alternative. In the present study, we propose and describe the properties of Ti-alkoxide as an alternative electron-accepting material to fullerene derivatives to create highly air-stable BHJ solar cells. It is well-known that controlling the morphology in the photoactive layer, which is constructed with fullerene derivatives as the electron acceptor, is important for obtaining a high overall efficiency through the solvent method. The conventional solvent method is useful for high-solubility materials, such as fullerene derivatives. However, for Ti-alkoxides, the conventional solvent method is insufficient, because they only dissolve in specific solvents. Here, we demonstrate a new approach to morphology control that uses the molecular bulkiness of Ti-alkoxides without the conventional solvent method. That is, this method is one approach to obtain highly efficient, air-stable, organic-inorganic bulk-heterojunction solar cells.

A method for fully printable, fullerene-free, highly air-stable, bulk-heterojunction solar cells based on Ti alkoxides as the electron acceptor and the electron-donating polymer fabrication is described here. Moreover, a method for controlling the morphology of the photoactive layer through the molecular bulkiness of the Ti-alkoxide units is reported.

The photoactive layer of a typical organic thin-film bulk-heterojunction (BHJ) solar cell commonly uses fullerene derivatives as the electron-accepting ...

Low Pressure Vapor-assisted Solution Process for Tunable Band Gap Pinhole-free Methylammonium Lead Halide Perovskite Films

Organo-lead halide perovskites have recently attracted great interest for potential applications in thin-film photovoltaics and optoelectronics. Herein, we present a protocol for the fabrication of this material via the low-pressure vapor assisted solution process (LP-VASP) method, which yields ~19% power conversion efficiency in planar heterojunction perovskite solar cells. First, we report the synthesis of methylammonium iodide (CH3NH3I) and methylammonium bromide (CH3NH3Br) from methylamine and the corresponding halide acid (HI or HBr). Then, we describe the fabrication of pinhole-free, continuous methylammonium-lead halide perovskite (CH3NH3PbX3 with X = I, Br, Cl and their mixture) films with the LP-VASP. This process is based on two steps: i) spin-coating of a homogenous layer of lead halide precursor onto a substrate, and ii) conversion of this layer to CH3NH3PbI3-xBrx by exposing the substrate to vapors of a mixture of CH3NH3I and CH3NH3Br at reduced pressure and 120 &#176;C. Through slow diffusion of the methylammonium halide vapor into the lead halide precursor, we achieve slow and controlled growth of a continuous, pinhole-free perovskite film. The LP-VASP allows synthetic access to the full halide composition space in CH3NH3PbI3-xBrx with 0&#160;&#8804; x&#160;&#8804; 3. Depending on the composition of the vapor phase, the bandgap can be tuned between 1.6 eV&#160;&#8804; Eg&#160;&#8804; 2.3 eV. In addition, by varying the composition of the halide precursor and of the vapor phase, we can also obtain CH3NH3PbI3-xClx. Films obtained from the LP-VASP are reproducible, phase pure as confirmed by X-ray diffraction measurements, and show high photoluminescence quantum yield. The process does not require the use of a glovebox.

Here, we present a protocol for the synthesis of CH3NH3I and CH3NH3Br precursors and the subsequent formation of pinhole-free, continuous CH3NH3PbI3-xBrx thin films for the application in high efficiency solar cells and other optoelectronic devices.

Organo-lead halide perovskites have recently attracted great interest for potential applications in thin-film photovoltaics and optoelectronics. Herein, ...

Recombination Dynamics in Thin-film Photovoltaic Materials via Time-resolved Microwave Conductivity

A method for investigating recombination dynamics of photo-induced charge carriers in thin film semiconductors, specifically in photovoltaic materials such as organo-lead halide perovskites is presented. The perovskite film thickness and absorption coefficient are initially characterized by profilometry and UV-VIS absorption spectroscopy. Calibration of both laser power and cavity sensitivity is described in detail. A protocol for performing Flash-photolysis Time Resolved Microwave Conductivity (TRMC) experiments, a non-contact method of determining the conductivity of a material, is presented. A process for identifying the real and imaginary components of the complex conductivity by performing TRMC as a function of microwave frequency is given. Charge carrier dynamics are determined under different excitation regimes (including both power and wavelength). Techniques for distinguishing between direct and trap-mediated decay processes are presented and discussed. Results are modelled and interpreted with reference to a general kinetic model of photoinduced charge carriers in a semiconductor. The techniques described are applicable to a wide range of optoelectronic materials, including organic and inorganic photovoltaic materials, nanoparticles, and conducting/semiconducting thin films.

A Time Resolved Microwave Conductivity technique for investigating direct and trap-mediated recombination dynamics and determining carrier mobilities of thin film semiconductors is presented here.

A method for investigating recombination dynamics of photo-induced charge carriers in thin film semiconductors, specifically in photovoltaic materials ...

Monovalent Cation Doping of CH3NH3PbI3 for Efficient Perovskite Solar Cells

Here, we demonstrate the incorporation of monovalent cation additives into CH3NH3PbI3 perovskite in order to adjust the optical, excitonic, and electrical properties. The possibility of doping was investigated by adding monovalent cation halides with similar ionic radii to Pb2+, including Cu+, Na+, and Ag+. A shift in the Fermi level and a remarkable decrease of sub-bandgap optical absorption, along with a lower energetic disorder in the perovskite, was achieved. An order-of-magnitude enhancement in the bulk hole mobility and a significant reduction of transport activation energy within an additive-based perovskite device was attained. The confluence of the aforementioned improved properties in the presence of these cations led to an enhancement in the photovoltaic parameters of the perovskite solar cell. An increase of 70 mV in open circuit voltage for AgI and a 2 mA/cm2 improvement in photocurrent density for NaI- and CuBr-based solar cells were achieved compared to the pristine device. Our work paves the way for further improvements in the optoelectronic quality of CH3NH3PbI3 perovskite and subsequent devices. It highlights a new avenue for investigations on the role of dopant impurities in crystallization and controls the electronic defect density in perovskite structures.

Monovalent Cation Doping of CH3NH3PbI3 for Efficient Perovskite Solar Cells

Here, we present a protocol to adjust the properties of solution-processed CH3NH3PbI3 through the incorporation of monovalent cation additives in order to achieve highly efficient perovskite solar cells.

Here, we demonstrate the incorporation of monovalent cation additives into CH3NH3PbI3 perovskite in order to adjust the optical, excitonic, and electrical ...

Flash Infrared Annealing for Perovskite Solar Cell Processing

Organic&#8211;inorganic perovskites have an impressive potential for the design of next generation solar cells and are currently considered for upscaling and commercialization. Currently, perovskite solar cells rely on spin-coating which is neither practical for large areas nor environmentally friendly. Indeed, one of the conventional and most effective lab-scale methods to induce perovskite crystallization, the antisolvent method, requires an amount of toxic solvent that is difficult to apply on larger surfaces. To solve this problem, an antisolvent-free and rapid thermal annealing process called flash infrared annealing (FIRA) can be used to produce highly crystalline perovskite films. The FIRA oven is composed of an array of near-infrared halogen lamps with an illumination power of 3,000 kW/m2. A hollow aluminum body enables an effective water-cooling system. The FIRA method allows the synthesis of perovskite films in less than 2 s, achieving efficiencies &#62;20%. FIRA has a unique potential for the industry because it can be adapted to continuous processing, is antisolvent-free, and does not require lengthy, hour-long annealing steps.

We describe a flash infrared annealing method used for the synthesis of perovskite and mesoscopic-TiO2 films. Annealing parameters are varied and optimized for processing on fluorine-doped tin oxide (FTO) glass and indium tin oxide-coated polyethylene terephthalate (ITO PET), subsequently giving devices power conversion efficiencies &#62;20%.

Organic&#8211;inorganic perovskites have an impressive potential for the design of next generation solar cells and are currently considered for upscaling ...

Environment

Facile Synthesis of Colloidal Lead Halide Perovskite Nanoplatelets via Ligand-Assisted Reprecipitation

In this work, we demonstrate a facile method for colloidal lead halide perovskite nanoplatelet synthesis (Chemical formula: L2[ABX3]n-1BX4, L: butylammonium and octylammonium, A: methylammonium or formamidinium, B: lead, X: bromide and iodide, n: number of [BX6]4- octahedral layers in the direction of nanoplatelet thickness) via ligand-assisted reprecipitation. Individual perovskite precursor solutions are prepared by dissolving each nanoplatelet constituent salt in N,N-dimethylformamide (DMF), which is a polar organic solvent, and then mixing in specific ratios for targeted nanoplatelet thickness and composition. Once the mixed precursor solution is dropped into nonpolar toluene, the abrupt change in the solubility induces the instantaneous crystallization of nanoplatelets with surface-bound alkylammonium halide ligands providing colloidal stability. Photoluminescence and absorption spectra reveal emissive and strongly quantum-confined features. X-ray diffraction and transmission electron microscopy confirm the two-dimensional structure of the nanoplatelets. Furthermore, we demonstrate that the band gap of perovskite nanoplatelets can be continuously tuned in the visible range by varying the stoichiometry of the halide ion(s). Lastly, we demonstrate the flexibility of the ligand-assisted reprecipitation method by introducing multiple species as surface-capping ligands. This methodology represents a simple procedure for preparing dispersions of emissive 2D colloidal semiconductors.

This work demonstrates facile room-temperature synthesis of colloidal quantum-confined lead halide perovskite nanoplatelets by ligand-assisted reprecipitation method. Synthesized nanoplatelets show spectrally narrow optical features and continuous spectral tunability throughout the visible range by varying the composition and thicknesses.

Inkjet Printing All Inorganic Halide Perovskite Inks for Photovoltaic Applications

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