Functionalized carbon derivative interconnected Bi₂S₃ composites for high-efficiency polymer solar cells and photo-detectors

This study presents a functional investigation of bismuth sulfide (Bi₂S₃) encapsulated carbon derivatives such as carbon nanotubes (CNT) and graphene oxide (GO) based PBDB-T:PCBM polymer composites for high-performance organic photovoltaics and X-ray detection applications. This work demonstrated the insertion of Bi₂S₃@CNT composites with an optimized amount of loading (1.5 wt%), to achieve power conversion efficiency of 9.51±0.25% in polymer solar cells (PSC) and a superior sensitivity of 3.14±0.03 mA/Gy·cm² in X-ray detectors. The optimized Bi₂S₃@CNT compressed device exhibited broad spectral response (∼80% EQE in visible light), high short-circuit current density (16.8±0.1 mA/cm²) and balanced charge transport for the PSCs. X-ray detection studies explored the significantly improved sensitivity and dark current characteristics in the Bi₂S₃@CNT composed device compared to pure and Bi₂S₃@GO doped active materials. The enhanced performance procured from the synergistic combination of the excellent photon absorption properties of Bi₂S₃ and efficient low-dimensional charge transport pathways of carbon derivatives (CNT or GO), which collectively improve charge generation, separation, and collection while minimizing recombination losses. Further, the Bi₂S₃-based carbon derivative composites showed dual functionality, interfacial energy alignment, enriched charge transport and scalable processing, making it a strong candidate for future optoelectronic, energy conversion, and radiation detection technologies.