Modification of copper-based chalcogenide nanocrystals' interconnections for efficient hole transportation in Perovskite solar cell

Cu-based chalcogenide p-type semiconductors in the form of nanocrystals can be used to deposit low-temperature and stable hole-transport layers (HTL) for n-i-p perovskite solar cells (PSCs). In this study, the synthesis parameters are modified to improve the hole-extraction of CuIn 0.75 Ga 0.25 S 2 (CIGS) layer. By optimizing the amount of oleylamine as the capping agent, the internal series resistance of PSCs decreases significantly while preventing aggregation of CIGS nanocrystals. Increasing the growth temperature from 220 °C to 275 °C leads to an increase in the size of CIGS nanocrystals. This results in an improvement in the open-circuit voltage of PSCs with FTO/c-TiO 2 /m-TiO 2 /Cs 0.05 (MA 0.17 FA 0.83 ) 0.95 Pb(I 0.83 Br 0.17 ) 3 /CIGS/Au structure from 0.941 to1.092 V, and Fill Factor from 60 to 73 on average. Finally, a nanocomposite of CIGS and a small amount of doped Spiro-OMeTAD is applied in PSCs with ITO/SnO 2 /(FA,MA)Pb(I,Cl,Br) 3 /HTL/Au structure. The achieved efficiency of 18.72% is comparable to that of PSCs with highly doped Spiro OMeTAD (18.5%).