Impact of Chemical Doping on Optical Responses in Bismuth-Doped CH3NH3PbBr3 Single Crystals: Carrier Lifetime and Photon Recycling

We studied the optical responses of organic–inorganic halide perovskite CH 3 NH 3 PbBr 3 single crystals doped with heterovalent Bi 3+ ions (electron densities up to 2.3 × 10 12 cm –3 ). The Bi doping causes no significant changes in the band gap energy but leads to an enhanced Urbach tail and photoluminescence blue shift. On the basis of the time-resolved photoluminescence measurements, we attribute the PL response to a shorter carrier lifetime induced by Bi doping, which results in a reduced photon recycling effect (i.e., the repeated emission and reabsorption of photons inside the crystal). We discuss the physical relation between Bi concentration and the optical and electric properties of Bi-doped CH 3 NH 3 PbBr 3 and reveal the unique nature of the Bi 3+ ion as a dopant in halide perovskites.