Large single-crystal flakes of 2D perovskite are able to sustain strong polariton nonlinearities at room temperature.

Charge generation and transport in (CH₃NH₃)PbI_3−xCl_x sensitized mesostructured solar cells are investigated. A highly efficient charge generation is directly proven by time correlated single photon counting analysis. Photoinduced absorption and transient photovoltage investigations depict double charge recombination dynamics. To explain the high device performances according to those spectroscopic observations, we suggest the existence of two complementary paths for electron transport, involving either TiO₂ or perovskite matrixes.