The Mixed Alloyed Chemical Composition of Chloro-(chloro) n -Boron Subnaphthalocyanines Dictates Their Performance as Electron-Donating and Hole-Transporting Materials in Organic Photovoltaics

Chloro­(chloro) n boron subnaphthalocyanine (Cl–Cl n BsubNc) from a commercial source and two synthetic routes were each tested as electron-donating and hole-transporting materials in planar as well as bulk heterojunction (PHJ and BHJ) organic photovoltaic (OPV) devices. We have previously reported that each Cl–Cl n BsubNc sample is a mixed alloyed composition, wherein each has a varying degree of bay-position chlorination. We have determined that increasing bay chlorination has a beneficial effect on the fill factor of PHJs. Comparison between this new and our past OPV data sets, which utilized the same set of Cl–Cl n BsubNcs as electron acceptors and transporters, reveals that the increase of fill factor and performance is likely due to improved exciton transport and higher levels of bay-position chlorination. While we identify two possible mechanisms for this, further studies will be required to determine whether the phenomenon is driven by decreased radiative relaxation or due to enhanced thermal hopping from a narrower density of states. We conclude that the usage of Cl–Cl n BsubNc with higher levels of bay-position chlorination, achieved through the “nitrobenzene process,” is likely to result in higher-performance OPVs.