Figure 1: Radiative efficiency of perovskite films.

(a) Steady-state absorption spectra measured with photothermal deflection spectroscopy (solid lines) and photoluminescence spectra (dashed lines) for MAPbX3 (X=I, Br, I1−xClx). (b) External PLQEs for MAPbI3−xClx on different substrates. The film on a textured substrate shows an external PLQE of 57%, three times higher than the planar film with 20% (indicated by dashed line).