Insights into the Failure Mechanisms of Organic Photodetectors

Abstract This work investigates in detail the reliability of poly(2,7‐carbazole‐alt‐4, 7‐dithienyl‐2,1,3‐benzothiadiazole):phenyl‐C61‐butyric acid methyl ester‐based organic photodiodes (OPDs) under visible light and air exposure. The current–voltage (I–V) characteristics of the state‐of‐the‐art OPDs are measured both at room and low temperature, before, during, and after ageing. While electrodes are only slightly impacted by ageing, the active layer is significantly damaged regardless the absence of UV light, leading to a major decrease in the responsivity. The combination of the thermally stimulated current and the I–V characteristics versus temperature (I–V–T) techniques along with the extensive use of the drift‐diffusion simulations all reveals that the observed degradation is the consequence of the generation of shallow traps (0.2 eV, N_T = 10¹⁶ cm⁻³) that significantly reduce the charge carrier mobility. In contrast, deep traps (0.7 eV, N_T = 7 × 10¹⁵ cm⁻³) are found to be present on freshly prepared samples and their concentration remains unchanged after ageing.