Effect of Extended Phenoxazine Central of Hole Transporting Materials in Perovskite Solar Cells

Based on the experimental molecule HTM1, the hole transport material HTM1-b was designed by extending the conjugation of the core group. The impact of different central donor units on the performance of hole transport materials was explored by studying their electronic, optical and excited-state properties. A comparison of the two hole transport materials revealed that the expansion of the central core lowers the HOMO energy level of hole transport material. HTM1-b exhibits a more stable structure, higher solubility and blue-shifted absorption peak. The smaller hole reorganization energy favours an improved hole mobility for HTM1-b. Consequently, employing HTM1-b as a hole transport layer will lead to enhanced efficiency in perovskite devices.