Performance improvement of perovskite solar cells via spiro-OMeTAD pre-crystallization

TLDR: In this article, the photovoltaic performance of perovskite solar cells (PSCs) was improved by solvent treatment of spiro-OMeTAD film processed from non-benzene solvent (ethyl acetate).

Abstract: Meticulous choice of hole transport materials (HTMs) is a crucial factor for carrier extraction and device stability in solar cells. 2,2′,7,7′-tetrakis-(N,N-di-4-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) as a HTM is a milestone in the development of perovskite solar cells (PSCs). Here, the photovoltaic performance of perovskite solar cells (PSCs) was improved by solvent treatment of spiro-OMeTAD film processed from non-benzene solvent (ethyl acetate). This treatment results in the pre-crystallization of spiro-OMeTAD, and thus an increased conductivity of the spiro-OMeTAD film. Via the solvent-treatment time, the highest power conversion efficiency of PSCs is improved to  ~ 19%, accompany with the enhancements of short-circuit current, open-circuit voltage, and fill factor. These improvements attribute to the reduced carrier accumulation and decreased serial resistance at the perovskite/spiro-OMeTAD interface. Thermal stability and lifetime of the PSCs based on the pre-crystallization spiro-OMeTAD are also improved. This solvent treatment to adjust the spiro-OMeTAD crystallization offers a facile yet effective way to fabricate high conduction layers toward environmentally friendly PSCs.