The outdoor lifetime and performance of organic photovoltaics (OPVs) using boron subphthalocyanine (BsubPc) derivatives as electron-accepting materials is presented. The protocols followed are based on the most advanced level of outdoor testing established by the International Summit on OPV Stability (ISOS). The stability of each BsubPc is compared using three different sets of encapsulated planar heterojunction OPVs, with each set containing a different BsubPc as the electron-accepting layer. The performance and stability of each set is tested outdoors using an epoxy glue and a glass coverslip as protection from the ambient environment. Outdoor testing continued until the OPVs reached 80 or 50% of their original power conversion efficiency, as determined by frequent indoor characterization. OPVs utilizing chloro-BsubPc are shown to exhibit the highest stability and performance, while the stability of the other two BsubPc derivatives is reduced presumably as a result of their phenoxy or phenyl functionalization in the molecular axial positions. The established structure–property relationship and guidance for the design of future compounds for application in planar heterojunction OPVs are contrary to, and could not have been anticipated from, time zero laboratory testing.

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In the field of organic photovoltaics (OPVs), outdoor stability research has lagged behind material development and device engineering. Testing protocols established at the International Summit of OPV Stability (ISOS) have stimulated some stability research, but these studies are almost exclusively limited to already-refined devices made with already-commercialized materials. If OPV materials were tested outdoors during small-scale stages, stability issues could be detected earlier in the development cycle. Chloro−(chloro) n −boron subnaphthalocyanine (Cl−Cl n BsubNc) is a material with high OPV performance but has not previously been tested outdoors. An OPV power conversion efficiency of 8.4% has been previously demonstrated for a trilayer stack containing α-sexithiophene, Cl−Cl n BsubNc, and chloro−boron subphthalocyanine (Cl−BsubPc). Building on the most advanced ISOS outdoor testing protocols (ISOS-O3), we assess the outdoor stability of small-scale bilayer and trilayer OPVs while establishing an improved stability screening method for future derivatives. The outdoor stability of Cl−Cl n BsubNc is determined to be comparable to that of Cl−BsubPc.

We demonstrate the first application of a unique boron subphthalocyanine (BsubPc) derivative, the oxygen bridged dimer μ-oxo-(BsubPc)2, as a multifunctional material within planar heterojunction organic photovoltaic (OPV) devices. We first explored the pairing of μ-oxo-(BsubPc)2 with well-known electron accepting and electron donating materials to explore its basic functionality. These preliminary device structures and metrics indicated that μ-oxo-(BsubPc)2 is best applied as an electron donating material when used in simple bilayer structures, as it yielded comparable OPV device efficiencies to that of the more well-established and highly optimized chloro-boron subphthalocyanine (Cl-BsubPc) OPV device structures. Thereafter we established that the HOMO/LUMO energy levels of μ-oxo-(BsubPc)2 are well-placed to apply it as a bifunctional donor/acceptor interlayer material in both energy and charge cascade OPV device architectures. Within this context, we found that μ-oxo-(BsubPc)2 was particularly effective in a charge cascade device as an interlayer between Cl-BsubPc and C70. We finally found evidence of an alloying-like effect for devices with mixed electron donor layers of (Cl-BsubPc) and μ-oxo-(BsubPc)2, achieved through co-deposition. The overarching conclusion is therefore that μ-oxo-(BsubPc)2 has the ability to improve the performance of Cl-BsubPc OPV devices and is a multifunctional material worthy of further study.

Chloro(chloro) n boron subnaphthalocyanine (Cl−Cl n BsubNc) from a commercial source and two synthetic routes were each tested as electron-donating and holetransporting 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.