Study and characterization of bulk heterojunction of P3HT/N2200 for use as active layer in flexible solar cells

In this article an optical, morphological and electric characterization of P3HT/N2200 diluted on chloroform was done with three weight ratios (4: 1, 1: 1 and 1: 4). This solvent was applied to verify if properties of mixtures of the two polymers provide characteristics for use as an active layer of an organic solar cell. The results show that the absorption spectra of the film mixtures have a large absorption band (350nm -800nm) while maintaining the positions of the P3HT and N2200 absorption peaks characterized separately. The images obtained of the P3HT/N2200 film morphology revealed the presence of percolation pathways that contribute to electrical conductivity in the films. A desired phase separation was also observed with well-defined domains, characterizing a BHJ, which is very important for the transport and transference of charge. The structure of the flexible photovoltaic device is composed of PET/ITO/PEDOT: PSS/P3HT: N2200/ZnO/Al. Only devices with P3HT/N2200 1: 1 ratio were tested, with and without heating at 100 degrees C. A photovoltaic effect was observed and the best device had a JSC of 1.20 mA/cm2, VOC of 0.52 V and PCE of 0.30%. Influence of the interface was noted between the domains of each polymer in the BHJ with a layer of ZnO, and it was concluded that this layer is important for improving the electrical performance of the device.