Amorphous TiO₂ Coatings Stabilize Perovskite Solar Cells

Significant progress has been achieved in improving the power conversion efficiency (PCE) of perovskite solar cells (PSCs) for a decade, but long-term stability is still underdeveloped. In regular PSC structure, 2,2?,7,7?-tetrakis(N,N-di-p-methoxyphenylamine)9,9?-spirobifluorene (Spiro-OMeTAD) with Li additives and metal electrodes are widely adopted, which leads to facile degradation under device operating conditions because ion migration. Herein, we show an interface-engineered stabilization approach prevent migration PSCs enabled by amorphous (a)-TiO2 capable hole transfer grown atomic layer deposition (ALD). This prevents consequent aggregation as well electrode diffusion into layer. Furthermore, combined layers Spiro-OMeTAD/a-TiO2 unprecedentedly promote efficiency, further verified other organic transport layers. Finally, operational TiO2-PSC substantially improved comparison that control PSC.