Expansion strategy of carbazole connecting unit in linear hole transport materials for perovskite solar cells

Hole transport materials (HTMs) play an important role in perovskite solar cells (PSCs), and the regulation of their molecular structures can promote the further development of power conversion efficiency (PCE) and stability. In this work, through exploiting the expansion strategy at the molecular level, a new linear HTM, named H580, was designed and synthesized by expanding the carbazole connecting unit. The results show that the introduction of dibenzol structure can significantly improve the photophysical and electrochemical characteristics of the molecule while preserving the passivating effect of the cyano group. The results show that a higher efficiency and a better stability are obtained after using H580 as the HTM. Significantly, compared with using spiro-OMeTAD alone, the additional introduction of H580 as an interface material with hole transport capability and defect passivation effect has achieved an excellent performance of PSCs.