‘Exploration of photovoltaic behavior of bithiophene-functionalized dispiro-oxepine based hole-transporting materials for efficient perovskite solar cells’

Abstract

Perovskite solar cells (PSCs) have received great attention from researchers due to their superior photovoltaic properties, high efficiency, and low cost. In this study, bithiophene dispiro-oxepine based five hole-transporting materials (DDOF1, DDOF2, DDOF3, DDOF4, and DDOF5) are designed by the substitution of end-capped acceptors via thiophene-based bridge to enhance the photovoltaic properties of PSCs. The results showed that designed HTMs have deeper HOMO levels (−4.88 eV to −5.04 eV), high solubility, and compatible stability with lower energy gaps (2.04 eV to 2.59 eV) than the reference (EHOMO = −4.55 eV, Eg = −3.49 eV) and Spiro-OMeTAD (EHOMO = −4.47 eV, Eg = −3.86 eV), which improved hole extraction and the open-circuit voltage in the PSCs. Moreover, the binding energy (0.41 eV to 0.46 eV) and TDM analysis indicated that DDOF1-DDOF5 HTMs have high charge mobility compared to the reference molecule DDOF (0.61 eV). The DDOF1-DDOF5 HTMs indicated anticipated higher power conversion efficiency and open-circuit voltage than the reference molecule. Overall, our findings proved that designed molecules are efficient HTMs for the manufacture of high-efficiency PSCs in the solar industry.