Enhancing Photomultiplication in Organic Photodetectors with Two-Dimensional Metal–Organic Framework Nanosheets

A broadband photomultiplication (PM)-type organic photodetector (OPD) is fabricated by incorporating ZnTCPP 2D metal–organic framework nanosheets (MONs) into a P3HT:PC 61 BM (100:1 w/w, 350 nm thick) active layer. When compared to pristine P3HT:PCBM-based OPDs, the optimized ZnTCPP-based PM OPD enhanced the performance of the detector in terms of EQE increasing to 4619 from 1330% and responsivity increasing to 15.8 from 4.2 A/W under 420 nm with an applied bias of −10 V. The addition of ZnTCPP increases the overall absorption of the active layer. It also alters the trap density and carrier transit time in the active layer, which leads to injection of more carriers through tunneling from the Al electrode to the HOMO of P3HT. The presence of ZnTCPP in the active layer also limits the decrease in response from its peak to 46%, which is approximately half of the reduction (83%) observed in the ZnTCPP-less OPD in the strong absorption region. The impact of thickness on the performance of the PM OPD is examined by increasing the thickness of the active layer from 350 to 450 nm. EQE decreases to 2806% at −10 V under 420 nm with the thicker active layer. The optimized ZnTCPP-based PM OPD also showed a detectivity of 10 11 Jones, a rise time ( t r ) of 220 ms, and a fall time ( t f ) of 160 ms. This is the first work to show that 2D metal–organic nanosheets have great potential to realize broadband PM OPDs, which have applications in image sensing and intelligent monitoring.