9.0% efficient Cu₂ZnSn(S,Se)₄ solar cells from selenized nanoparticle inks

Abstract

Thin‐film solar cells using Cu2ZnSn(S,Se)4 absorber materials continue to attract increasing attention. The synthesis of kesterite Cu2ZnSnS4 nanoparticles by a modified method of hot injection is explained. Characterization of the nanoparticles by energy dispersive X‐ray spectroscopy, X‐ray diffraction, Raman, and transmission electron microscopy is presented and discussed. When suspended in an ink, coated, and processed into a device, the nanoparticles obtained by this synthesis achieve a total area (active area) efficiency of 9.0% (9.8%) using AM 1.5 illumination and light soaking. This improvement over the previous efficiency of 7.2% is attributed to the modified synthesis approach, as well as fine‐tuned conditions for selenizing the coated nanoparticles into a dense absorber layer. Copyright © 2014 John Wiley & Sons, Ltd.

Easy and low-cost aqueous precipitation method to obtain Cu2ZnSn(S, Se)4 thin layers

“…In addition, selenization is totally avoided, thus it is environmental positive. Other routes based on nanoparticles 23 , solvothermal [24][25][26] , rotatory ball milling 27 , microwave 28 , hot-injection 25,[29][30][31][32] or non-injection methods 33 , spray pyrolisis 34 have been also applied, but with inferior effectiveness for CZTSSe production.…”

Synthesis of large CZTSe nanoparticles through a two-step hot-injection method

“…Various alternatives to hydrazine do exist, and several organic solvents can be utilized. 4,[7][8][9][10] However, none was able to reach an efficiency close to the hydrazine route.…”

“…Nanoparticle deposition methods such as doctor blading (η=9% (CZTSSe)) 7 , spin coating (η=7.7% (CZTSSe)) 8 , spray coating (η=1.4% (CZTSe)) 9 , drop casting (η=0.74% (CZTSSe)) 4 and ink-jet printing (η=4.46% (CZTSSe)) 10 have been attempted by many groups. The best device of pure phase CZTS NPs has an efficiency of 2.5% 11 .…”

“…13,[16][17][18][19][20][21] Zaberca et al 18 find that the large particles are only partially crystallized. The best solar cell efficiencies have been obtained for nanoparticles synthesized through the hot-injection approach 7 , and for NPs synthesized through hot-injection, the average particle size is closer to the crystallite size. 4,5,7,9,11,[22][23][24][25][26][27][28][29][30][31][32][33][34] Previous NP syntheses suggest that larger particle sizes can be obtained through longer reaction duration 27 and using chalcogenide precursors with slower reaction rates 29 but so far these changes only resulted in anisometric particles of ~40 nm (in length) and ~25 nm (in diameter).…”

“…The best solar cell efficiencies have been obtained for nanoparticles synthesized through the hot-injection approach 7 , and for NPs synthesized through hot-injection, the average particle size is closer to the crystallite size. 4,5,7,9,11,[22][23][24][25][26][27][28][29][30][31][32][33][34] Previous NP syntheses suggest that larger particle sizes can be obtained through longer reaction duration 27 and using chalcogenide precursors with slower reaction rates 29 but so far these changes only resulted in anisometric particles of ~40 nm (in length) and ~25 nm (in diameter). Zhou et al 30 find that the particle size increased at higher reaction temperatures -with 8 nm at 240 o C and 16 nm at 280 o C. In other fields of nanotechnology, larger particles have been synthesized by controlling the ligand-particle interaction and the number of nuclei initially formed 36,37 based on a paper by Yin and Alivatos 38 .…”