Density of bulk trap states of hybrid lead halide perovskite single crystals: temperature modulated space-charge-limited-currents

Abstract

Temperature-modulated space-charge-limited-current spectroscopy (TMSCLC) is applied to quantitatively evaluate the density of trap states in the band-gap with high energy resolution of semiconducting hybrid lead halide perovskite single crystals. Interestingly multicomponent deep trap states were observed in the pure perovskite crystals, which assumingly caused by the formation of nanodomains due to the presence of the mobile species in the perovskites.

Space-charge-limited electron and hole currents in hybrid organic-inorganic perovskites

“…Analysis of the relative permittivity. In the analysis of the current-voltage characteristics of MAPbI 3 perovskite solar cells in literature thus far, the dielectric constant (ε) was assumed to be frequency independent, having constant values typically ranging from 6 to 117 7,19,35,[37][38][39][40][41][42][43][44]46,[48][49][50][51][53][54][55][56][57][58][59] . Also for other perovskites, the relative permittivity in the SCLC analysis was taken to be constant 7,19,[38][39][40][42][43][44]46,[48][49][50][51]53,54,58,59 .…”

“…Application of the SCLC model disregarding the effects of ions on permittivity and field distribution then leads to erroneous results regarding chargecarrier mobility and trapping sites. Although there are numerous publications on SCLC measurements of perovskite single crystals and thin films, the effect of mobile ions, permittivity, and temperature on the current-voltage behavior are missing 7,19,[38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54] . To date, an accurate description of SCLCs in perovskite thin films does not exist.…”

Extraction technique of trap states based on transient photo-voltage measurement

“…There are only few methods for the extraction of DOS T distribution. The space charge limited current (SCLC) method uses the deconvolution to extract the DOS T distribution [35][36][37][38][39][40] , based on the measured J-V data at different temperatures. Walter et al [41][42][43][44][45] put forward the impedance spectroscopy (IS) method to extract the DOS T distribution.…”

“…SCLC measurement gives the relation of current density and voltage at different temperatures (j = j (U, T)). For SCLC method, we extract the DOS T distribution adopting the equations listed as follows [35][36][37][38][39][40] (26) www.nature.com/scientificreports/ constant of perovskite absorber layer. Based on the SCLC measurement result, we need to calculate E a , m, B, C and finally use Eq.…”

“…Based on the SCLC measurement result, we need to calculate E a , m, B, C and finally use Eq. (30) to extract the DOS T by deconvolution [35][36][37][38][39][40] . The calculations of E a , m, B, C are complicated.…”