A novel and cost effective CZTS hole transport material applied in perovskite solar cells

In the present study, we aimed to investigate the possibility of CZTS as a low-cost inorganic hole transport material (HTM). Hitherto, numerous researchers have reported the synthesis of CZTS nanoparticles (NPs) in specific atmospheric conditions. In the present study, the CZTS NPs were synthesized under ambient conditions by a sol-gel method. Furthermore, the effect of aging time on the size of NPs was studied by altering the aging time (3, 6 and 12 h). The size of the NPs was measured using a DLS Nano Zetasizer. Additionally, the size of the NPs was confirmed by scanning electron microscopy analysis. The smallest size of 400-500 nm was achieved by 3 h of aging. Furthermore, in the present study, an SnCl2-doped perovskite (CH3NH3Pb1-xSnxI3-yCly) was synthesized. The as-prepared CZTS NPs were applied as a low-cost eco-friendly HTM to replace the expensive and volatile (toxic) conventional spiro-MeOTAD in perovskite solar cells (PSC). In order to apply CZTS NPs as an HTM in PSC, nanoink was prepared by dispersing CZTS NPs in methanol. The combination of a CZTS NPs and SnCl2-doped perovskite (CZTS-PVSK) is reported for the first time. Additionally, for comparison, spiro-MeOTAD as an HTM-based PSC was also fabricated. A promising solar cell efficiency of 9.66% was achieved by CZTS-perovskite solar cells with a marginally higher stability. Hence, the present study demonstrates the great potential of CZTS as a low-cost, environmentally friendly HTM in PSCs.