Theoretical study of photovoltaic performance for inverted halide perovskite solar cells

Abstract

The existence of serious hysteresis effect for regular perovskite solar cells (PSCs) will affect their performances, however, the inverted PSCs can significantly suppress the hysteresis effect. To data, it has been very rarely reported to simulate the inverted planar heterojunction PSCs. In this paper, the effects of hole transport material (HTM), electron transport material (ETM), and ITO work function on performance of inverted MAPbI₃ solar cells are carefully investigated in order to design the high-performance inverted PSCs. The inverted MAPbI₃ solar cells using Cu₂O, CuSCN, or NiO<i>_x</i> as HTM, and PC₆₁BM, TiO₂, or ZnO as ETM are simulated with the program AMPS-1D. Simulation results reveal that i) the inverted MAPbI₃ solar cells choosing NiO<i>_x</i> as HTM can effectively improve the photovoltaic performance, and the excellent photovoltaic performance obtained by using TiO₂ as ETM is almost the same as by using ZnO as ETM; ii) the ITO work function increasing from 4.6 eV to 5.0 eV can significantly enhance the photovoltaic performances of Cu₂O— based and CuSCN— based inverted MAPbI₃ solar cells, and the NiO<i>_x</i>— based inverted MAPbI₃ solar cells have only a minor photovoltaic performance enhancement; iii) based on the reported ITO work function between 4.6 eV and 4.8 eV, the maximum power conversion efficiency (PCE) of 27.075% and 29.588% for CuSCN— based and NiO<i>_x</i>— based inverted <i>MA</i>PbI₃ solar cells are achieved when the ITO work function reaches 4.8 eV. The numerical simulation gives that the increase of hole mobility in CuSCN and NiO<i>_x</i> for ITO/CuSCN/MAPbI₃/TiO₂/Al and ITO/NiO<i>_x</i>/MAPbI₃/TiO₂/Al can greatly improve the device performance. Experimentally, the maximum hole mobility 0.1 cm²·V^–1·s^–1 in CuSCN restricts the photovoltaic performance improvement of CuSCN— based inverted MAPbI₃ solar cells, which means that there is still room for the improvement of cell performance through increasing the hole mobility in CuSCN. It is found that NiO<i>_x</i> with a reasonable energy-band structure and high hole mobility 120 cm²·V^–1·s^–1 is an ideal HTM in inverted MAPbI₃ solar cells. However, the increasing of electron mobility in TiO₂ cannot improve the device photovoltaic performance of inverted MAPbI₃ solar cells. These simulation results reveal the effects of ETM, HTM, and ITO work function on the photovoltaic performance of inverted MAPbI₃ solar cells. Our researches may help to design the high-performance inverted PSCs.