Exciton dynamics and photoresponse behavior of the in situ annealed CsSnBr₃ perovskite films synthesized by thermal evaporation

Abstract

The CsSnBr3 photodetectors are fabricated by thermal evaporation and 75°C in-situ annealing, and the effect of in-situ annealing on the morphology, structure, exciton dynamics and photoresponse of thermally evaporated CsSnBr3 films are investigated. Especially, temperature-dependent steady-state photoluminescence (PL) and transient PL decaying have been analyzed in details for understanding the exciton dynamics. Meanwhile, effect of annealing on the activation energy for trap sites (Ea), exciton binding energy (Eb), activation energy for interfacial trapped carriers (ΔE), trap densities and carriers mobilities are studied and the annealed (A-CsSnBr3) reveals obviously lower Eb and trap density together with notably higher carrier mobility than those of the unannealed (UA-CsSnBr3). Temperature dependence of the integrated PL intensity can be ascribed to the combining effect of the exciton dissociation, exciton quenching through trap sites and thermal activation of trapped carriers. The temperature dependent transient PL decaying analysis indicates that the PL decaying mechanism at low and high temperature is totally different from that in intermediate temperature range, in which combing effect of free exciton and localized state exciton decaying prevail. The beneficial effects of the in-situ annealing on the photoresponse performance of the CsSnBr3 films can be demonstrated by the remarkable enhancement of the optimal responsivity (R) after in-situ annealing which increases from less than 1A/W to 1350A/W as well as dramatically improved noise equivalent power (NEP), specific detectivity D* and Gain (G).

Exciton dynamics and photoresponse of a CVD-grown WS2/thermally evaporated CsSnBr3 heterostructure

“…For isolated CsSnBr 3 films, all the TRPL curves could be well fitted by a biexponential function, in which the fast decay component could be ascribed to the surface recombination of electron–hole pairs while the slow component could be attributed to the edge state recombination. 41,50 The exciton lifetime of the isolated CsSnBr 3 increased from 2.15 to 4.64 ns at 680 nm with increasing the thickness from 10 to 70 nm, and was comparable to those reported in the previous literature, 51 also manifesting the satisfactory quality of the thermally evaporated CsSnBr 3 in our study. Such TRPL trace behavior was consistent with the PL behavior of the CsSnBr 3 films, as shown in Fig.…”

High-throughput screening of the transport behavior of tetragonal perovskites

“…The experimental values of CsSnI 3 and CsSnBr 3 were μ h = 585 cm 2 V −1 s −1 and μ e = 119–847 cm 2 V −1 s −1 , respectively. 28,88 It was noted that the mobility predicted by the LAP model was much higher than the experimental values; therefore, the LAP for perovskite materials was not a decisive scattering source. Previous investigations had revealed that the LAP might overestimate mobility.…”

Biaxial strain improving carrier mobility for inorganic perovskite: ab initio Boltzmann transport equation

“…Due to the morphology of the samples and measurement methods, it is difficult to obtain the intrinsic mobility of perovskite in the experiment. The experimental mobility was 0.23-270 cm 2 V −1 s −1 for CsPbI 3 [16][17][18][19][20][21], 1.05 × 10 −3 -585 cm 2 V −1 s −1 for CsSnI 3 [22][23][24][25][26][27][28], 41.3-1000 cm 2 V −1 s −1 for CsPbBr 3 [29][30][31], and 119-847 cm 2 V −1 s −1 for CsSnBr 3 [32]. The theoretical mobility was 68-2820 cm 2 V −1 s −1 for CsPbI 3 [33][34][35][36][37], 370.5-1500 cm 2 V −1 s −1 for CsSnI 3 [38][39][40][41], 39-2710 cm 2 V −1 s −1 for CsPbBr 3 [38,42,43], and 260-511 cm 2 V −1 s −1 for CsSnBr 3 [37,38].…”