NIR Photoresponse of Perovskite Solar Cells with Titanyl Phthalocyanine

The effect of titanyl phthalocyanine TiOPc in the methylammonium lead triiodide (MAPbI3) perovskite based solar cells is studied. The photovoltaic output of cells at low intensity illumination with lmax= 840 nm is greatly enhanced when using TiOPc as a NIR-absorbing hole conductor. Compared to the reference cells with a standard cuprous iodide CuI as a hole-transporting layer, the photocurrent increases by a factor of 15, so that the narrow-band power conversion efficiency (PCE) exceeds 2 %. It should be pointed out that the irradiation wavelength lies beyond the intrinsic absorption of MAPbI3 or any other material in the device scheme except TiOPc. The improvement is associated with the photoactivity of TiOPc molecules in the near infrared region due to the largely splitted Q-band, as confirmed by the dependence of parameters on the polymorph transition in the TiOPc films.