Modeling Photovoltaic Performances of BTBPD-PC61BM System via Density Functional Theory Calculations

Designing and fabricating high-performance photovoltaic devices have remained a major challenge in organic solar cell technologies. In this work, the photovoltaic performances of BTBPD-PC61BM system were theoretically investigated by means of density functional theory calculations coupled with the Marcus charge transfer model in order to seek novel photovoltaic systems. Moreover, the hole-transfer properties of BTBPD thin-film were also studied by an amorphous cell with 100 BTBPD molecules. Results revealed that the BTBPD-PC61BM system possessed a middle-sized open -circuit voltage of 0.70 V, large short-circuit current density of 16.874 mA/cm(2), large fill factor of 0.846, and high power conversion efficiency of 10%. With the Marcus model, the charge-dissociation rate constant was predicted to be as fast as 3.079x10(13) s(-1) in the BTBPD-PC61BM interface, which was as 3-5 orders of magnitude large as the decay (radiative and non-radiative) rate constant (10(8)-10(10) s(-1)), indicating very high charge-dissociation efficiency (similar to 100%) in the BTBPD-PC61BM system. Furthermore, by the molecular dynamics simulation, the hole mobility for BTBPD thin-film was predicted to be as high as 3.970x10(-3) cm(2)V(-1)s(-1), which can be attributed to its tight packing in solid state.