Current-voltage analysis of annealing effects of poly(3-hexlythiophene) and phenyl-C61-butyric acid methyl ester organic solar cells

The field of organic photovoltaics (OPV) has progressed rapidly. With new materials and methods being briskly developed, the characterization of OPV also needs to be updated. Current-voltage (JV) analysis of poly(3-hexlythiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) OPV devices yield valuable insight into the internal physics of devices. A simple lumped circuit model, previously used to analyze various inorganic thin-film PV and more recently applied to OPV, has been used to study annealing parameters. To investigate the change in the lumped circuit model parameters, we carried out an annealing study of P3HT: PCBM blend OPV devices. We annealed devices at various temperatures and before and after evaporating the contact. We characterized and quantified the effect of thermal annealing by studying how the model parameters changed. We found that all parameters studied reacted favorably to annealing, including device resistances and parameters measuring recombination. While studying the resistances in unannealed and annealed devices, a barrier was found around the flat band voltage. This barrier disappeared upon annealing, indicating that it was due to material characteristics related to the crystallinity or the phase separation. The data were used to better characterize annealing effects. (C) 2013 Society of Photo-Optical Instrumentation Engineers (SPIE)