Improvement of P3HT–ICBA solar cell photovoltaic characteristics due to the incorporation of the maleic anhydride additive: P3HT morphology study of P3HT–ICBA and P3HT–ICBA–MA films by means of X-band LESR

A light-induced electron spin resonance (LESR) X-band study of poly(3-hexylthiophene)/indene-C60 bisadduct P3HT/ICBA flexible solid films containing the additive maleic anhydride (MA) is presented. An increase of P3HT crystalline domain orientation in P3HT:ICBA:MA in comparison with P3HT:ICBA films was confirmed by the angular LESR spectra dependence of P3HT positive polarons. It was assumed that the average increase of power conversion efficiency in P3HT:ICBA:MA solar cells films, relative to P3HT:ICBA, is connected with the more effective crystalline P3HT phase orientation due to the MA sublimation from the composites blends during annealing. The relative average increase of power conversion efficiency of SC films containing MA in comparison to pure P3HT:ICBA blends is estimated to be a factor of (1.15) higher, while the concentrations of functional composites (polymer/fullerene) in blends made with MA decrease by up to 25–30%.