Interfacial Layer Materials with a Truxene Core for Dopant-Free NiO-Based Inverted Perovskite Solar Cells.

Nickel oxide (NiO) is commonly used as a holetransporting material (HTM) in p-i-n perovskite solar cells. However, the weak chemical interaction between the NiO and CHNHPbI (MAPbI) interface results in poor crystallinity, ineffective hole extraction, and enhanced carrier recombination, which are the leading causes for the limited stability and power conversion efficiency (PCE). Herein, two HTMs, TRUX-D1 (N,N,N-tris(9,9-dimethyl-9H-fluoren-2-yl)-5,5,10,10,15,15-hexaheptyl-N,N,N-tris(4-methoxyphenyl)-10,15-dihydro-5H-diindeno[1,2-a:1',2'-c]fluorene-2,7,12-triamine) and TRUX-D2 (5,5,10,10,15,15-hexaheptyl-N,N,N-tris(4-methoxyphenyl)-N,N,N-tris(10-methyl-10H-phenothiazin-3-yl)-10,15-dihydro-5H-diindeno[1,2-a:1',2'-c]fluorene-2,7,12-triamine), are designed with a rigid planar C symmetry truxene core integrated with electron-donating amino groups at peripheral positions.