The photoluminescent polarization properties of organic halide
perovskites are of great importance for the fundamental understanding
and for device fabrication, while limited relevant work has been
published. In this work we investigate the fluorescence polarization
properties of the CH3NH3PbI3, CH3NH3PbI3−xClx, and CH3NH3PbBr3
perovskites which have been used in some of the highly efficient solar
device to date. Time-resolved fluorescence anisotropy measurements were
conducted on these perovskites fabricated by different methods, and with
or without the capping hole transport layer. We demonstrate that CH3NH3PbBr3 perovskite exhibits isotropic fluorescence polarization while CH3NH3PbI3 and CH3NH3PbI3−xClx
perovskites exhibit anisotropic fluorescence polarization. The
composition influences significantly fluorescence anisotropy dynamics
while fabrication has relatively weaker influence. The hole transport
capping layer can accelerate the decay of the fluorescence anisotropy.
The symmetry of perovskite structure is proposed to be the key factor to
impact the fluorescence anisotropy.