Double injection in organic bulk-heterojunction

Abstract

We have used double injection current (DoI) transient technique for investigation of mobility, recombination and deep trapping of charge carriers in bulk-heterojunction organic solar cells, where bimolecular charge carrier recombination is reduced compared to Langevin recombination. Experimental DoI transient’s investigation results of RRP3HT/PCBM blends were compared with ones of a-Si:H solar cells, and with results obtained by both charge carrier extraction (CELIV) and time-of-flight (TOF) techniques. Numerical modeling of DoI transient, taking into account charge carrier trapping, demonstrated that in bulk-heterojunction organic material blends the influence of charge carrier deep trapping is insignificant. The bimolecular recombination coefficient is strongly reduced compared to Langevin recombination one and depends on the density of charge carriers.