Stable decaphenylcyclopentasilane hole transport layers for double-stacked perovskite photovoltaic devices fabricated under ambient atmosphere

Stable decaphenylcyclopentasilane (DPPS) hole transport layers were developed for guanidinium-, formamidinium-, or ethylammonium-added double-stacked CH₃NH₃PbI₃ perovskite photovoltaic devices without using 2,2′,7,7′-tetrakis (N,N-di-p-methoxyphenylamino)-9,9′-spirobifluorene, which is a typical hole transport layer. Stacking two types of perovskite compounds inserted within the DPPS layer enabled the fabrication of stable perovskite solar cells under ambient atmosphere at 190 ​°C, which reduced the trap density and improved the photovoltaic properties of the devices. As expected, the DPPS-inserted layers functioned as a stable hole transport layer for perovskite solar cells.