Investigations of the incident light angle effect on the organic photovoltaics devices performance using varied acceptor ratio

Abstract

Organic photovoltaic devices (OPV) have received great attention in the last decades, due to their advantages in fabrication processes and the low cost of organic material. In this report, the active layer of the device is prepared from poly (3-hexylthiophene) (P3HT) (20 K): (phenyl C61 butyric acid methyl ester) (PCBM) with various acceptor ratios (1:0.5–2). The surface morphology of the active layer thin films was investigated by analysing their optical microscope image using Image J software. The active layer thin films were characterized optically to calculate the optical properties of the active layer. The internal absorption of the device is calculated using the optical modelling technique. Then, optical modelling is utilized to optimize the device performance based on changing the donor: acceptor ratio and predicting the internal quantum efficiency (IQE) of the devices. The optimum current density values of the device (Jsc) were found to vary in about (11–14 mA cm−2) compared with the measured data (3.8–8 mA cm−2). The internal quantum efficiency (IQE) was identified from measured and modelled Jsc and its percentage confirmed that the best blending ratio of P3HT: PCBM is (1:0.8–1), associated with the IQE percentage 54%–45%. Additionally, the effect of incident light angle was examined by using optical modelling technique and the findings revealed that the current density Jsc, gradually increased with the incident angle between (0–45) degrees and then suddenly decrease at the angle of 60 degrees due to the reflection that occurs at Air/glass interface at large angles.