A Nonlinear Electric Model of the Transient Photoelectric Current in an Organic Photodiode

One of the possible causes of the degradation of organic photodiodes is explained in terms of a nonlinear resistance–capacitance model. Electronic switches for switching photodiode parameters when light is turned on and off are used as nonlinear elements in the equivalent circuit. The model treats the photodiode as a spatially localized photovoltage generator loaded on a passive four-terminal device connected with the electrodes through passive interface layers. The presence of passive layers that have areas with oppositely directed built-in pulling electric fields is the main cause of the degradation of photodiode characteristics. The proposed equivalent circuit well reproduces the experimental transient and steady-state processes in organic photodiodes and can be useful both for measuring the electrical parameters of photodiodes and for studying the processes leading to their degradation.