Taewan Kim¹ Guan-Woo Kim¹ Minjun Kim¹ Junwoo Lee¹ Taiho Park¹

1, POSTECH, Pohang, , Korea (the Republic of)

Compact TiO₂ is well-known electron transport material in sensitized solar cells and perovskite solar cell. However, because of the unsuitable energy level and slow electron extraction of TiO₂, the planar TiO₂ perovskite solar cell showed low power conversion efficiency with high hysteresis. Here, the planar TiO₂ electron transport layer is modified with p-type CuI for perovskite solar cells. It is found that the polarity of the CuI-modified TiO₂ surface pull electrons to the surface of the TiO₂, which improves electron extraction and makes barrier-free energy level. Furthermore, the radiative recombination is also reduced by high extraction. The final device shows a 19.0% high efficiency with reduced hysteresis by removal of trap s<span style="font-size:10.8333px">tate</span>.