Polyvinylcarbazole as an Efficient Interfacial Modifier for Low-Cost Perovskite Solar Cells with CuInS2/Carbon Hole-Collecting Electrode

Different polymers have been already introduced for passivating the interfacial defects at the interface of perovskite and the organic hole transport material, meanwhile as an environmental barrier in perovskite solar cells (PSCs). Herein, polyvinylcarbazole (PVK) compared to polymethylmethacrylate (PMMA) at the interface of the perovskite (Cs-0.05(MA(0.83)FA(0.17))(0.95)Pb(Br0.17I0.83)(3)) layer and CuInS2/carbon as a low-cost inorganic hole-collecting electrode are investigated. By suppressing interfacial recombination using PMMA and PVK, saturation current density (in dark current) decreases one order of magnitude from 7.9 x 10(-10) to 4.0 x 10(-11) mA cm(-2) by adding PMMA and two orders of magnitude to 9.4 x 10(-12) mA cm(-2) by adding PVK. By decreasing charge-transfer resistance (measured by impedance spectroscopy), fill factor is increased (from 0.61) to 0.62 and 0.69, respectively. The efficiency of PSC with PVK/CuInS2/carbon hole-collecting electrode is 17.69% that is significantly higher and more reproducible than that of PMMA/CuInS2/carbon and CuInS2/carbon hole-collecting electrodes. It seems these interfacial layers also act as a barrier against penetration of carbon black and CuInS2 nanoparticles through the perovskite holes and have the functionality of a binder layer to improve the interfacial area.