A Comparative Study of Linear and Starburst Ethane-Based Hole Transporting Materials for Perovskite Solar Cells

Recently, linear and starburst hole transporting materials (HTMs) have been widely developed as potential alternatives to conventional spiro-OMeTAD in perovskite solar cells (PSCs). Herein, two facile ethane-based HTMs with linear or starburst shape have been designed and prepared. The molecular structures variation on the photophysical, electrochemical, hole mobility, hydrophobicity, film-forming ability and photovoltaic properties in PSCs are comprehensively investigated. Interestingly, the linear molecule exhibits bathochromic-shift spectra, slightly lower HOMO energy level, higher hole mobility and better hydrophobicity than their starburst counterpart. Moreover, photoluminescence study confirmed that linear molecule can efficiently extract holes at perovskite/HTM interface rather than starburst one. Consequently, a higher efficiency of 16.85% for the doped linear molecule based device is obtained compared to that of starburst counterpart exhibiting a lower efficiency of 14.87%. Moreover, linear HTM a...