Research On Planar Perovskite Solar Cells Via Low-pressure Vapor-assisted Solution Process With Electron Collection Bilayer

Because of the advantage of longer charge diffusion length,high light absorption coefficient and suitable bang gap,The materials of Organic-inorganic halide lead perovskite have been received widespread concern.In our study,perovskite solar cells（PSCs）with the configuration of FTO/compact TiO₂/CH3NH3 Pb I3/Spiro-OMe TAD/Au was obtained via a low-pressure vapor assisted solution process.The optimized PSC can achieve a PCE of 10.61%,with a FF of 60.82% measured under reverse voltage scanning.In perovskite solar cells,electron transporting layers play a critical role in blocking holes and transporting electrons for high performances.So PCBM layer was introduced by a solution-process method between TiO₂ layer and CH3NH3 Pb I3 layer,which was also synthesized via a low-pressure vapor assisted solution process.The PSCs with TiO₂/PCBM bilayer were obtained and the optimized PSC can achieve a PCE of 14.75%,with a FF of 65.58% measured under reverse voltage scanning.PCBM layer enhances the PCE of PSCs and alleviates hysteresis of PSCs.Furthermore,fullerene layer was introduced by a solution-process method between TiO2 layer and CH3NH3 Pb I3 layer,which was also synthesized via a low-pressure vapor assisted solution process.The PSCs with TiO₂/fullerene bilayer were obtained and the optimized PSC can achieve a PCE of 16.58%,with a FF of 75.91% measured under reverse voltage scanning.The results show that the electron transporting bilayer dramatically enhances cell performance and alleviates hysteresis of PSCs even part of fullerene dissolved in DMF solution.When fullerene was used as the single electron transporting layer,the PCE is only 4.29%,because of the incomplete coverage of fullerene on FTO substrate.Additionally,PSCs with fullerene interface layers showed far less hysteresis than reference cells without fullerene layers.Analysis of the equivalent circuit of devices and fluorescence lifetime measurements focusing on the CH3NH3 Pb I3 film with electron transporting bilayer confirms that fullerene facilitates electron injection from CH3NH3 Pb I3 into the compact TiO₂ layer in our device configuration.