Investigation of the Current of P3HT: PCBM-Based Organic Solar Cell Extracting the Spatial Recombination Coefficient of the Active Layer

The current of P3HT:PCBM-based organic solar cells was analytically investigated in this work. Position-and wavelength-dependent excitons generated by light were evaluated using the optical transfer matrix method. The charge carriers generated by dissociating excitons were estimated using an improved dissociation probability, incorporating a Gaussian distribution. A universal analytical equation was derived by solving the transport equation to calculate the current-producing holes and electrons. Similarly, another universal equation was derived to calculate the hole and electron currents. The total current, calculated using a constant recombination coefficient, is found to be different at different positions (position dependent), which is inconsistent because the total current should be position independent. The use of a constant recombination coefficient is the reason for this inconsistent result. The spatial recombination coefficients inside the active layer were extracted and used in the calculation, and the total current was found to be position independent; thus, the inconsistency was resolved. The current and its components have been investigated with respect to position, terminal voltage, solar irradiance, active layer thickness and wavelength. This work provides better results because it includes spatial recombination coefficients, space-and wavelength-dependent excitons, and improved dissociation probability in analytical calculations; therefore, it will help improve the prediction and design of organic solar cells.