Pyridine-triphenylamine hole transport material for inverted perovskite solar cells

In the light of superior interaction between pyridine unit and perovskite, a facile star-shaped triphenylamine-based hole transport material (HTM) incorporating pyridine core (coded as H-Pyr) is designed and synthesized. A reference HTM with benzene core, coded as H-Ben, is also prepared for a comparative study. The effects of varying core on HTMs are investigated by comparing the photophysical, electrochemical and hole mobility properties. It is found that pyridine core exhibits better conjunction and decreased dihedral angles with triphenylamine side arms than that of benzene, leading to obviously better hole mobility and well-matched work function. The perovskite film prepared on H-Pyr also shows improved crystallization than on H-Ben. Photoluminescence and electrochemical impedance studies indicate improved charge extraction and reduced recombination in the H-Pyr-based perovskite solar cells. Consequently, H-Pyr-based device exhibits higher efficiency than H-Ben-based one. After doping with a Lewis acid, tris(pentafluorophenyl)borane, H-Pyr-based device delivers a champion efficiency of 17.09%, which is much higher compared with 12.14% of the device employing conventional poly(3,4-ethy lenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as HTM. Moreover, the H-Pyr-based device displays good long-term stability that the power conversion efficiency remains over 80% of the initial value after storage in ambient (relative humidity = 50 +/- 5%) for 20 days. (C) 2020 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

A facile star-shaped hole transport material (HTM) incorporating pyridine core (H-Pyr) was designed and synthesized, showing better hole mobility and well-matched work function compared with a benzene core HTM (H-Ben). The perovskite solar cells using H-Pyr exhibited improved crystallization, charge extraction, and reduced recombination, resulting in higher efficiency and long-term stability compared to H-Ben-based cells. Doping with a Lewis acid further enhanced the efficiency of the H-Pyr-based devices, making them a promising alternative to conventional HTMs like PEDOT:PSS.