Enhancing performance of a photomultiplication-based broadband photodetector with porphyrin MOF-ZnO nanocomposite

Abstract

In this work, a nanocomposite using ZnTCPP MOF and ZnO nanoparticles is synthesized. A broadband photodetector is optimized using this nanocomposite to enhance the performance of a photomultiplication-based organic photodetector. Various weight percentages (w/w%) of ZnO were incorporated in the ZnTCPP metal-organic framework precursor during synthesis, and material parameters were analyzed via structural and chemical analysis methods. These nanocomposites were incorporated in the P3HT:PCBM matrix in a 1:1:0.5 wt ratio, and photodetectors were fabricated with an inverted structure (ITO/TiO₂/Active Layer/Al). A reference device with P3HT:PCBM and ZnO nanoparticles is fabricated and compared. Photomultiplication is observed in all the devices, with the devices with nanocomposite showing enhanced quantum efficiency and responsivity. The best-performing ZnTCPP@ZnO-based device reported the highest EQE of 10827 % at 510 nm for a given bias of −5 V. Photomultiplication is attributed to the trap states created due to the TiO₂/active layer interface and the presence of ZnO in the active material. ZnO acts as a hole-blocking component, giving rise to charge accumulation and, subsequently, tunneling electrons. These devices have shown high responsivity (44.53 A/W), small rise time/fall time (61.7 ms/107.6 ms), and high detectivity (7.2 × 10¹¹ Jones) at a given bias voltage of −5 V.