Influence of charge transporting layers on ion migration and interfacial carrier recombination in CH3NH3PbI3 perovskite solar cells

Migration of ionic defects and energy band diagram of p-i-n device at short circuit and forward bias conditions. [Display omitted] •In perovskite layer, differential ionic distribution causes dynamic electric field.•Ion migration and interfacial recombination are the dominate causes of hysteresis.•Increased charge accumulation/recombination leads to lower Voc.•Passivation of traps by PCBM suppresses hysteresis and improves carrier extraction. Using the transient Sun–Voc measurements it has been demonstrated that not only ion migration but charge accumulation/recombination at perovskite/charge transporting layer interfaces also plays a significant role in the hysteresis of J-V curves in perovskite solar cells. The transient ideality factor was investigated for two different architectures of perovskite devices. The wide range variation of transient ideality-factor implies that different ionic distribution causes change in recombination mechanisms. Owing to the passivation effect induced by PCBM, the iodine ions/vacancies were significantly reduced. These findings indicate the importance of efficient charge transfer and reduction of defects/ion accumulation at interfaces for device stability.