Enhanced Long‐Term Stability of Perovskite Solar Cells Employing a Benzodithiophene Derivative‐Based Dopant‐Free Hole Transporting Layer

Perovskite solar cell (PSC) is characterized by high photoelectric conversion efficiency (PCE) and low material cost compared to the silicon solar cell that has already been commercialized. Many researchers are conducting various studies to improve efficiency and stability. To increase power conversion efficiency, hole transporting materials (HTMs) are one of the most important factors for achieving high performance in PSCs. HTMs exhibit an important role in PSCs to transfer the positive charges in between perovskite and counter electrodes. Among the various HTMs, Spiro-OMeTAD has been widely used in PSCs. However, due to its reliance on additives to enhance hole mobility, Spiro-OMeTAD suffers from degradation issues that compromise its long-term stability. So, it is necessary to develop new HTMs to replace Spiro-OMeTAD for their low stability and expensiveness in future application of PSCs. Therefore, we designed and synthesized the materials named PEH-23 and PEH-24 incorporating dialkoxyphenyl and dialkoxybenzodithiophene. As the conjugation length increases, the material demonstrates improved stability, suggesting its potential as an effective HTM with long-term reliability.