• Liu, H.; Liu, H.R.; Yang, F.; Yang, J.E.; Song, J.; Li, M.; Li, Z.; Tsoi, W.C.; Chinweokwu Eze, M.; Liu, Z.Y.; Ma, H.; Gao, M.; Wang, Z.K.: π-Conjugated small molecules enable efficient perovskite growth and charge-extraction for high-performance photovoltaic devices. Journal of Power Sources 448 (2020), p. 227420/1-8

10.1016/j.jpowsour.2019.227420
Open Access Version

Abstract:
A π-conjugated small molecule N,N′-bis(naphthalen-1-yl)-N,N’+-bis(phenyl)benzidine (NPB) is introduced into a poly (bis(4-phenyl)(2,4,6-trimethylphenyl)amine) (PTAA) hole transport layer in inverted perovskite solar cells (PSCs). The NPB doping induces better perovskite crystal growth owing to a strong π-π interaction with PTAA and cation-π interactions with CH3NH3+ (MA+). In addition, NPB doping not only improves the wettability of PTAA and regulates the perovskite crystallization to achieve a larger grain size, but also moves the valence band energy of the hole transport layer closer to the perovskite layer. Consequently, the fabricated PSCs delivered a power conversion efficiency (PCE) of 20.15%, with a short-circuit current density (JSC) of 22.60 mA/cm2 and open-circuit voltage (VOC) of 1.14 V. This outcome indicates that PTAA:NPB composite materials present great potential for fabricating high-performance PSCs.