Research on the multiplication mechanism of single-carrier transport-based multiplication-type organic photodetector

Abstract

Multiplication-type organic photodetectors exhibit advantages such as high gain, broad spectral response, flexibility, and low cost, making them promising candidates for applications in weak light detection, biomedical imaging, wearable devices, and optical communication. To explore the multiplication mechanism of single-carrier-transport-based multiplication-type organic photodetectors, this study has fabricated electron trap-type organic photodetectors with a structure of ITO/PEDOT: PSS/Active-layer/Al using the solution spin-coating method, and the active layers(ACL) were composed of binary blends of classical systems of P3HT:PC₆₁BM (100:1, wt/wt), PBDB-T: ITIC (100:1, wt/wt), or PTB7:PC₇₁BM (100:1, wt/wt). The absorption spectra of the active layers and the external quantum efficiency of the devices were measured, and the light intensity distribution and the distribution of photogenerated charge carriers in the devices were simulated and calculated. By comparing the absorption spectra of the active layers, the external quantum efficiency of the devices, and the distribution curve of photo-generated electrons near the Al electrode, it can be concluded that the multiplication effect in the single-carrier-transport-based multiplication-type organic photodetector is explained by the quantum tunneling injection of holes into the external circuit, which is induced by charge trapped by the interface trap near the aluminum electrode. This study provides valuable insights into the multiplication mechanism of multiplication-type organic photodetectors, offering a theoretical basis for the development and fabrication of high-performance multiplication-type organic photodetectors.