Enhanced long-term stability of perovskite solar cells using a double-layer hole transport material

The instability of hybrid organic-inorganic perovskite solar cells hinders their commercialization and further applications although they have reached high power conversion efficiency. Here we introduce a double-layer hole transport material into perovskite solar cells containing a CuSCN layer and spiro-OMeTAD layer simultaneously. Consequently, the long-term stability of the solar cells was significantly enhanced compared to those of single-layer devices and the devices can sustain about 90% of their initial power conversion efficiency after 10 hours of continuous working at the maximum power point. We ascribed the long-term stability enhancement to the suppression of methylamine migration by the CuSCN layer.