Physical engineering of anti‐solvents in perovskite precipitation for enhanced photosensitive affinity

Abstract

Summary For the development of the perovskite formation process, it is necessary to explore the principle of fabricating the photosensitive layer. Herein, a novel perspective on the physical properties of anti‐solvents is proposed, which is related to perovskite crystallization. Specifically, we focus on aromatic solvents with different functional groups as anti‐solvents (methylbenzene (MB) and chlorobenzene (CB)). This is because the precursor solubility depends on the interactions with each solvent, which is closely observed via FT‐IR. In this context, the interfacial affinity of thin perovskite layer induced uniform morphology of electron transport layer (ETL). This phenomenon is characterized by FE‐SEM, AFM, and XRD in detail. Based on these data, CB‐treated perovskite photodetector exhibits superior detectivity and fast response speed owing to better interfacial affinity between perovskite and ETL. Also, improved charge dynamic behavior (dark current and impedance analysis) was observed in CB‐treated condition. Therefore, it is demonstrated that the selection of anti‐solvent is important to optimize morphological affinity between perovskite and interlayer in fabricating thin photosensitive layer, which contributes to realization of fast and highly sensitive photodetector.

Large Grains and Shallow Defect States by Early Crystal Growth Suppression for High Responsivity in Perovskite Photodetectors

“…Since the grain boundaries are pathways for electrons to pass through, the ethyl ether-treated PD showed a higher shunt leakage current than the other PDs with small grains . The toluene-treated device exhibited a smaller resistance than the devices treated with the other two washing solvents, which resulted from the relatively thin structure with larger grains than the CB-treated perovskite grains …”

“…35 The toluene-treated device exhibited a smaller resistance than the devices treated with the other two washing solvents, which resulted from the relatively thin structure with larger grains than the CB-treated perovskite grains. 36 Dark current was generated by the charge injection current along the main junction as well as the shunt leakage current. 37,38 The charge injection current can be identified from the slope after the shunt leakage region in Figure 5a.…”