A review on conventional perovskite solar cells with organic dopant-free hole-transport materials: roles of chemical structures and interfacial materials in efficient devices

Abstract

Perovskite solar cells (PSCs) have established themselves as a highly efficient and low-cost photovoltaic technology. However, the stability issues associated with charge transport materials still limit the lifetime of PSCs, especially in conventional PSCs. Doped spiro-OMeTAD serves as the state-of-the-art hole transport material (HTM) for conventional PSCs, but it induces a large trade-off between efficiency and stability. Tremendous efforts have been devoted to developing dopant-free HTMs and strategies for achieving efficient and stable PSCs, and efficiencies above 24% have been achieved. To promote the further development of conventional PSCs with dopant-free HTMs, there is a clear need to understand the structure–property correlation of dopant-free HTMs and optimize the perovskite/HTM interface. Herein, this review collects the organic dopant-free HTMs-based conventional PSCs with efficiencies above 20%, giving an overview of the relationship between the chemical structure and material properties of HTMs. Particularly, the roles of interfacial materials in these devices, including additives in perovskite films and additional interlayers, are discussed. Finally, an outlook is presented for the further development of conventional PSCs with dopant-free HTMs.