Charge Carrier Recombination Dynamics in MAPb(Br1−yIy)3 Single Crystals

Abstract

Studying the carrier recombination process in MAPb(Br1−yIy)3 single crystals (SCs) is important for its application in the optoelectronic field. In this work, a series of MAPb(Br1−yIy)3 SCs with varied Br/I compositions have been studied. Steady-state photoluminescence (PL) spectra, time-resolved photoluminescence (TRPL) spectra and time-resolved microwave photoconductivity (TRMC) were used to understand the radiative and non-radiative recombination processes of MAPb(Br1−yIy)3 SCs. By comparing the dynamics of TRPL and TRMC, we conclude that the dynamics of TRPL is dominated by the electron trapping process, which is in accordance with the fast decay component of TRMC kinetics, whereas the slower decay component in TRMC is dominated by the hole trapping process. Moreover, we find both the electron and hole trapping rates in mixed-halide perovskite MAPb(Br1−yIy)3 (0 < y < 1) SCs are higher than that of mono-halide perovskite MAPbBr3 SCs and MAPbI3 SCs. This suggests mixed-halide crystals could introduce additional electron and hole trapping densities, which could be related to the fluctuation of Br/I compositions in the crystals. This work is helpful for understanding carrier recombination process in mixed-halide perovskite SCs.

Photoexcited Carrier Dynamics in Iodine-Doped CH3NH3PbBr3 Single Crystals

“…As shown in Figure b, we noticed the decay of PL kinetics became faster upon adding iodine content. Diverging from other researches, we observed that the PL decay kinetics did not vary monotonically with the increase of iodine . Instead, the PL kinetics becomes faster at x = 0.10, slows down at x = 0.20, and then becomes faster again at x = 0.33.…”

“…Diverging from other researches, we observed that the PL decay kinetics did not vary monotonically with the increase of iodine. 15 Instead, the PL kinetics becomes faster at x = 0.10, slows down at x = 0.20, and then becomes faster again at x = 0.33. We summarize the effective lifetimes τ e extracted from the inset of Figure 2b of these crystals in Figure 2d.…”

“…14 Xiao et al investigated the carrier recombination dynamics of MAPb-(Br 1−y I y ) 3 single crystals by time-resolved photoluminescence (TRPL) and time-resolved microwave photoconductivity (TRMC) measurements, disclosing the relationship between the Br/I fraction and the electron and hole trapping density. 15 Most of the aforementioned studies were based on the bromide incorporated APbI 3 , due to the suitable bandgap for optoelectronic devices, while the partial substitution of iodine into the bromine sites in APbBr 3 system was less mentioned. Sujith and co-workers elaborated the decrease of defect density with iodine doping in CsPbBr 3 single crystals.…”

“…Rehman et al studied the charge carrier dynamics of FAPb­(Br y I 1– y ) 3 film and obtained the correlation between the recombination rate constant (bimolecular and Auger recombination) and Br/I fraction . Xiao et al investigated the carrier recombination dynamics of MAPb­(Br 1– y I y ) 3 single crystals by time-resolved photoluminescence (TRPL) and time-resolved microwave photoconductivity (TRMC) measurements, disclosing the relationship between the Br/I fraction and the electron and hole trapping density …”

Charge Carrier Recombination Dynamics in MAPb(BrxCl1–x)3 Single Crystals

“…In addition, TRPL of MAPb(Br x Cl 1– x ) 3 single crystals was measured to understand carrier recombination processes. Generally, carrier recombination dynamics in semiconductors can be described by the following equation: − normald n ( t ) normald t = prefix− k n ( t ) − γ n ( t ) 2 − A n ( t ) 3 where k , γ, and A are the first-order, second-order, and Auger recombination coefficients, respectively. We observe that TRPL kinetics of MAPb(Br x Cl 1– x ) 3 single crystals exhibit non-exponential decay behaviors, as shown in Figure a.…”