A new strategy for monitoring the charge transfer from perovskite thin films to electron transport layers using a heterodyne transient grating technique

Abstract

We fabricated CH3NH3PbI3 (MAPbI3) thin films with and without a ZnO layer and measured heterodyne transient grating (HD-TG) responses of each film to investigate the charge injection dynamics from MAPbI3...

Monitoring Charge Transfer Dynamics of Surface Trapped Holes in ZnO Surface Utilized for Ethanol Oxidation Using Heterodyne Transient Grating Spectroscopic Techniques

“…It implies that the second components could be assigned to the recombination arising from the surface trapped electrons, based on its retardation in the presence of the hole scavenger (ethanol), which is consistent with the former study. 38 it was also noticeable that only two components were found even in ethanol when Λ was 80 μm as shown in Table 1b, which could be attributed to the accidental overlap of two components (A 1 exp(−t/τ 1 ) and A 1 exp(−t/τ 2 ) in eq 2).…”

“…The time constants of the second components (τ 2 in eqs and ()), which were not assigned to the thermal diffusion, were approximately 1 × 10 –4 s in ACN and 8 × 10 –4 s in ethanol, respectively, regardless of Λ. It implies that the second components could be assigned to the recombination arising from the surface trapped electrons, based on its retardation in the presence of the hole scavenger (ethanol), which is consistent with the former study . it was also noticeable that only two components were found even in ethanol when Λ was 80 μm as shown in Table b, which could be attributed to the accidental overlap of two components ( A 1 exp­(– t /τ 1 ) and A 1 exp­(– t /τ 2 ) in eq ).…”

“…Thus, the latter one could be attributed to thermal diffusion, based on the assignments in the former studies. 28,38 In ethanol, as given in Table 1b, three distinct components were extracted from the observed response presented in Figure 2b. As can be seen in the table and the response in the figure, the time constants of the second and third components (τ 2 and τ 3 in eq 2) were not significantly influenced by changing Λ, while that of the first component (τ 1 in eq 2) was affected.…”

“…[32][33][34]36,38 For example, we were able to observe the recombination of the trapped electrons at the surface of ZnO, transferred from MAPbI 3 , to determine the electron transfer efficiency from the perovskite material to the electron transport layer. 38 In addition, we studied the recombination arising from surface-trapped holes and the charge transfer kinetics of long-lived holes in α-Fe 2 O 3 -and BiVO 4 -based photoanodes. [32][33][34]36 In this study, we investigated the photoexcited charge carrier dynamics in ZnO using the NF-HD-TG technique to understand its photocatalytic degradation efficiency.…”

“…In the previous studies in which the NF-HD-TG technique was utilized, the dynamics of photoexcited charge carriers in various types of solar energy materials and solar cells have been investigated. − ,, For example, we were able to observe the recombination of the trapped electrons at the surface of ZnO, transferred from MAPbI 3 , to determine the electron transfer efficiency from the perovskite material to the electron transport layer . In addition, we studied the recombination arising from surface-trapped holes and the charge transfer kinetics of long-lived holes in α-Fe 2 O 3 - and BiVO 4 -based photoanodes. − , …”