Charge‐Carrier Trapping and Radiative Recombination in Metal Halide Perovskite Semiconductors

Abstract

Trap-related charge-carrier recombination fundamentally limits the performance of perovskite solar cells and other optoelectronic devices. While improved fabrication and passivation techniques have reduced trap densities, the properties of trap states and their impact on the charge-carrier dynamics in metal-halide perovskites are still under debate. Here, a unified model is presented of the radiative and nonradiative recombination channels in a mixed formamidinium-cesium lead iodide perovskite, including charge-carrier trapping, de-trapping and accumulation, as well as higher-order recombination mechanisms. A fast initial photoluminescence (PL) decay component observed after pulsed photogeneration is demonstrated to result from rapid localization of free charge carriers in unoccupied trap states, which may be followed by de-trapping, or nonradiative recombination with free carriers of opposite charge. Such initial decay components are shown to be highly sensitive to remnant charge carriers that accumulate in traps under pulsedlaser excitation, with partial trap occupation masking the trap density actually present in the material. Finally, such modelling reveals a change in trap density at the phase transition, and disentangles the radiative and nonradiative charge recombination channels present in FA 0.95 Cs 0.05 PbI 3, accurately predicting the experimentally recorded PL efficiencies between 50 and 295 K, and demonstrating that bimolecular recombination is a fully radiative process.

Nanoscale interfacial engineering enables highly stable and efficient perovskite photovoltaics

“…For both films, we observe two features: a rapid decay within the first 5 ns followed by an almost monoexponential slower decay. The fast decay at early times has been attributed to initial carrier trapping, 54 and hole transfer, 55 whereas the following slower decay, is caused by non-radiative recombination. 56 Note that with the low fluences used here, radiative bimolecular and non-radiative Auger recombination are negligible.…”

Enhanced Hole‐Carrier Selectivity in Wide Bandgap Halide Perovskite Photovoltaic Devices for Indoor Internet of Things Applications

“…Furthermore, the diffusion rate of the mobile ions has been shown to decrease when long chain alkylammonium cations are used in low‐dimensional perovskites, which could further contribute to constraining the ionic movement at the HTL/perovskite interface of the 2 mg PEAI deposited device. [ 34 ]…”

Halide perovskite composites for photocatalysis: A mini review

“…The value of μ in the prototypical polycrystalline MAPbI 3 was reported in the range from 0.2 to 100 cm 2 V −1 second −1 . The charge carrier properties of halide perovskites are largely dependent on their crystal size and structure 26,39‐42 . Xing et al uncovered that the solution processed polycrystalline MAPbI 3 had a long‐range, balanced electron‐hole diffusion length of at least 100 nm 43 .…”