Charge Transport and Extraction of Bilayer Interdiffusion Heterojunction Organic Solar Cells

Bilayer interdiffusion heterojunction with the structure of a donor-rich region near the anode and an acceptor-rich region near the cathode could weaken the energy-level barrier between the active layer and electrode and improve the performance of organic solar cells. In this study, the poly(3-hexylthiophene)/[6:6]-phenyl-C61-butyric acid bilayer interdiffusion heterojunction organic solar cells were prepared using the orthogonal solvent method and the charge transport and extraction characteristics were investigated in detail. The transient photovoltage/transient photocurrent measurements showed that the bilayer interdiffusion heterojunction devices have a longer carrier recombination lifetime and a shorter charge extract time, and a higher carrier mobility of the bilayer interdiffusion device was verified by photoinduced charge carrier extraction by linearly increasing the voltage technology. The results indicated that the improved heterojunction structure of the bilayer interdiffusion devices could reduce the carrier recombination and improve the charge transport and extraction efficiency. The performance of the bilayer interdiffusion device was enhanced obviously, and about 19.8% power conversion efficiency improvement was achieved as compared with the bulk device. Bilayer interdiffusion heterojunction provides an efficient device structure to optimize the performance of organic solar cells.