ScholarWorks@숙명여자대학교

초록

Photodetectors (PDs) play crucial roles in various optoelectronic applications. Metal oxide/organic semiconductor junction-based PDs are particularly promising because they exhibit excellent responsivity, detectivity, and fast broadband response. Among conductive polymers, polythiophenes are good candidates for use as light absorbers and hole-transport layers in PDs owing to their facile thin-film processability and robust environmental stability. However, achieving high conductivity remains challenging, primarily because of their intrinsically low carrier density and limited crystallinity. These characteristics directly affect charge-transfer efficiency and overall device performance. In this study, we introduced silver trifluoroacetate (AgTFA) as a hole dopant for poly(3-hexylthiophene) (P3HT), leading to the formation of highly dense nanowire networks during spin coating. The high solubility of AgTFA in aromatic solvents enabled strong coordination between Ag+ ions and thiophene units, promoting pi-pi stacking along the [010] direction. Furthermore, efficient Ag+ doping significantly enhanced the conductivity from 8.71 & times; 10-4 to 8.11 S cm-1. The underlying doping and nanowire formation mechanisms were elucidated using density functional theory calculations, which identified the optimized doping sites. SnO2, deposited by atomic layer deposition, served as both light absorber and electron transport layers. Interestingly, the roles of SnO2 and P3HT interchanged depending on the wavelength, with ultraviolet and visible light primarily absorbed in SnO2 and P3HT, respectively. Owing to the enhanced conductivity of P3HT, the resulting PDs exhibited outstanding responsivity (32.9-104.6 mA W-1), detectivity (4.58 & times; 1012-1.21 & times; 1013 Jones), and external quantum efficiency (8.75%-43.26%), comparable to those of high-performance organic and perovskite PDs.

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