Micrometer Sized Perovskite Crystals in Planar Hole Conductor Free Solar Cells

In this work we demonstrate the planar configuration on hole conductor (HTM) free perovskite based solar cells. The CH 3 NH 3 PbI 3 perovskite was deposited using the spray technique to achieve micrometer size perovskite crystals. The number of spray passes changes the CH 3 NH 3 PbI 3 film thickness; for example, 10 spray passes achieved a film thickness of 3.4 μm of perovskite. Surprisingly, power conversion efficiency of 6.9% was demonstrated for this novel, simple solar cell structure with thick perovskite film that has no HTM. Capacitance–voltage measurements reveal charge accumulation at the CH 3 NH 3 PbI 3 /Au interface while the compact TiO 2 /CH 3 NH 3 PbI 3 junction showed a space charge region, which inhibits the recombination. Studying these interfaces is key to understanding the operation mechanism of this unique solar cell structure. This simple planar HTM free perovskite solar cell demonstrates the potential to make large-scale solar cells while maintaining a simple, low-cost architecture.