Highly stable and efficient solid-state solar cells based on methylammonium lead bromide (CH3NH3PbBr3) perovskite quantum dots

Easy processability and high stability are key features of methylammonium lead bromide (CH3NH3PbBr3)-based perovskite solar cells. The main focus of the present work was to fabricate and evaluate the stability of CH3NH3PbBr3 quantum dot (QD)-based perovskite solar cells. We used an ex situ solution process to synthesize CH3NH3PbBr3 QDs and then successfully fabricated mesoscopic solid-state perovskite solar cells. We also studied the influence of different CH3NH3PbBr3 QD sizes and different hole-transporting materials (HTMs), 2,2',7,7'-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene (spiro-MeOTAD) and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), on the solar cell performance. The size of the CH3NH3PbBr3 QDs was controlled by the solution processing parameters. Our controlled results show that spiro-MeOTAD- and PTAA-based devices exhibited, respectively, an open-circuit voltage (V-OC) of 0.991 and 1.091 V and a current density (J(SC)) of 11.68 and 12.05 mA cm(-2), which resulted in an average power conversion efficiency (PCE) of 7.35 and 9.44% under a standard 100 mW cm(-2) illumination without masking. Our best-performing cell, which contains the FTO/Bl-TiO2/mp-TiO2+CH3NH3PbBr3 (similar to 2-nm QDs)/PTAA/Au configuration shows the following results: open-circuit voltage (V-OC) = 1.110 V, current density (J(SC)) = 14.07 mA cm(-2), fill factor = 0.73 and an 11.40% PCE. Furthermore, the CH3NH3PbBr3-based devices are stable for more than four months.