A model for the J-V characteristics of P3HT:PCBM solar cells

Current-voltage (J-V) characteristics of an organic bulk heterojunction solar cell have been modeled and compared with the measured characteristics of solar cell based on the blend of poly(3-hexylethiophene) (P3HT) and phenyl [6,6] C(61) butyric acid methyl ester (PCBM). In an undoped organic double Schottky junction diode, for V < V(bi) the electric field remains constant and is given by (V(bi)-V)/d, where V(bi) is the built-in voltage, V is the applied voltage, and d is sample thickness. We considered the effect of this constant electric field on the charge carrier transport and solved the drift and diffusion equations to model the J-V characteristics. For V < V(bi) the current is found to be dominated by diffusion. A comparison of the theoretical results with the experimental data measured in dark and under different illumination intensities shows good agreement.