The influence of axial fluorination of SubPc on the photoresponse performances of small-molecule organic photodiodes

Boron subphthalocyanine (B-Cl-SubPc) and its derivatives have been widely employed in organic photovoltaic (OPV) devices owing to the tailorability of their photophysical and photoelectronic behaviors arising from the diversity of possible halogen modifications of the complex. However, there are few reports on organic photodiode (OPD) devices comprising B-Cl-SubPc and the aforementioned derivatives; in particular, their photoresponsivities have been rarely reported. Herein, we explore the influence of the axial fluorination of SubPc on the photoresponsivity of OPD devices with bulk heterojunction (BHJ) configurations. Novel surface photovoltage (SPV) analysis combined with air photoemission spectroscopy was used to elucidate the specific roles of the rapid decay and intrinsic trap state in accelerating the photoresponsivity of fluorinated SubPc. Moreover, these results indicate that advanced computational techniques, including molecular dynamics (MD) and density functional theory (DFT) calculations, can be used to obtain deeper insights, for example based on electron hopping rates and energy disordering, into the mechanisms underlying experimental results.