Improving Zero-Voltage Photo Detection in Flexible OPDs with a PFN-Br Electron Transport Layer

This work explores the fabrication and characterization of flexible organic photodetectors (OPDs) made of conductive poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) anode on PET substrate and focuses on overcoming the low responsivity challenges of these flexible OPDs at zero bias. The work demonstrates a 1.51 times increased dark current and 1.6 times decreased photo current at zero bias in flexible OPDs with PEDOT:PSS anodes on PET substrate compared to the traditional rigid OPDs with ITO anodes on glass substate. The introduction of Poly(9,9-bis(3’-(N,N-dimethyl)-N-ethylammoinium-propyl-2,7-fluorene)-alt-2,7-(9,9 dioctylfluorene))dibromide (PFN-Br) as an Electron Transport Layer (ETL) in the flexible OPDs decreases the dark current by 1.25 times and increases the photocurrent, responsivity, built in potential and depletion width by 1.34, 1.048 and 1.4 times, respectively at zero bias in the flexible OPDs. This work shows the potential of PFN-Br ETL as a solution to challenges in flexible OPDs.