Multifunctional Two-Dimensional Conjugated Materials for Dopant-Free Perovskite Solar Cells with Efficiency Exceeding 22%

Fu, Q (Fu, Qiang)^{[ 1,2 ]} ; Xu, ZY (Xu, Zhiyuan)^{[ 1,2 ]} ; Tang, XC (Tang, Xingchen)^{[ 1,2 ]} ; Liu, TT (Liu, Tingting)^{[ 1,2 ]} ; Dong, XY (Dong, Xiyue)^{[ 1,2 ]} ; Zhang, XD (Zhang, Xiaodan)^{[ 3,4 ]} ; Zheng, N (Zheng, Nan)^{[ 5 ]} ; Xie, ZQ (Xie, Zengqi)^{[ 5 ]} ; Liu, YS (Liu, Yongsheng)^{[ 1,2,4 ]}

ACS ENERGY LETTERS, 2021, 6(4): 1521-1532

DOI: 10.1021/acsenergylett.1c00385

摘要

Replacing the dominated hole transport material (HTM), doped Spiro-OMeTAD, in state-of-the-art perovskite solar cells (PSCs) is a challenge but an urgent issue for commercialization of this technology. Here, a solution-processable two-dimensional (2D) polymer HTM, namely, 2DP-TDB, which featuring with extended pi-electron delocalization into the two-dimensions, has been successfully developed. It is found that 2DP-TDB shows multifunctional characteristics, such as dominant face-on packing orientation, good charge transport properties, efficient perovskite surface passivation capability. and hydrophobicity. As a result, planar n-i-p structured PSCs employing 2DP-TDB as dopant-free HTM exhibit a high efficiency of 21.53%, which is much larger than that using a control 2D small molecule (TB-DPP) (11.61%). Importantly, after further optimization of the perovskite film with the formamidine-based spacer, the devices based on dopant-free 2DP-TDB HTM show a champion efficiency as high as 22.17%. This work offers a fundamental strategy by developing 2D conjugated polymer HTMs for dopant-free PSCs with both high efficiency and stability.