Improving the Performance of Perovskite Solar Cells Through Solvent Vapor Annealing-based Morphology Control of the Hole-Transport Layer

Abstract

In this work, we improved the performance of perovskite solar cells (PSCs) by controlling the morphology of 22'.7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD) layers using a solvent vapor annealing method. We found that this technique could result in a smoother morphology of the spiro-OMeTAD layer, which further improved the contacts at the perovskite/spiro-OMeTAD and spiro-OMeTAD/Au interfaces. Consequently, the power conversion efficiency (PCE) of PSCs improved from 14.62 to 16.73% along with simultaneous enhancements of the open-circuit voltage, short-circuit current density. and fill factor. The hysteresis of the PSCs decreased significantly from 4.4 to 0.6%. Moreover, the degradation in the PCE of the PSCs for long-term storage was reduced from 19 to 14% over the period of 144 hours. The best PSC based on a solvent vapor-annealed spiro-OMeTAD layer exhibited a high PCE of 17.15% with a stable power output. Our results indicate that using solvent vapor annealing to control the morphology of spiro-OMeTAD layers is an effective method for fabricating high-performance PSCs.