Exciton–exciton scattering in perovskite CH₃NH₃PbBr₃ single crystal

Abstract

We have measured photoluminescence spectra in CH3NH3PbBr3 at low temperatures and found a nonlinear emission at the lower energy side of the exciton resonance. Considering that this signal shows a rapid decay, we have assigned it as originating from the exciton–exciton inelastic scattering process called P-emission. The energy difference between this P-emission and the free exciton resonance is 20–30 meV, which is consistent with recent studies of the exciton binding energy.

Indirect tail states formation by thermal-induced polar fluctuations in halide perovskites

“…As mentioned, the origins of the dual PL peaks in perovskite SCs (and also reported for PC TF) are still under intense debate. Explanations range from (1) lateral inhomogeneities and coexistence of structural phases 13,18 ; (2) defect bound carriers or bound exciton emission 12 ; (3) surface versus bulk emission 14,15 ; (4) free carrier versus exciton emission 17 ; (5) phonon replica 26 ; (6) inelastic exciton–exciton scattering (P emission) 27 , exciton–electron scattering (H emission) or biexciton emission; and (7) the reabsorption effect 16,28–30 . However, none can satisfactorily account for the dual PL peaks and its universal nature.…”

Observation of Net Stimulated Emission in CsPbBr3 Thin Films Prepared by Pulsed Laser Deposition

“…The energy separation between exciton absorption peak and stimulated emission peak, 54 meV, largely exceeds biexciton binding energy value (ranging from 1/10 to 1/5 of exciton binding energy [ 33 ] ). Biexciton mechanism can be ruled out.…”

Free and self-trapped exciton emission in perovskite CsPbBr3 microcrystals

“…17 Similar phenomenon in hybrid halide perovskites such as CH 3 NH 3 PbX 3 (X ¼ Br, I) was advised to be from free carriers and exciton recombination, 18 the transverse inhomogeneity and structure coexistence, [19][20][21] and the inelastic exciton-exciton scattering or biexciton emission. 22 Emission spectra with three peaks were assigned to two BEs and an FE emission. 23,24 Even without observation of two or more luminescence peaks, the low-temperature PL spectrum of CsPbX 3 usually reveals an asymmetric tail in the low-energy side of the FE peak, implying the existence of some weak components.…”