Investigating the Effect of Exposure Time and Humidity on P3HT Decay through Photoluminescence Emission

Poly-3-hexylthiophene (P3HT), though an archetypal donor in organic photovoltaic devices (OPVs), suffers from degradation in the ambient environment. Thus, P3HT is widely studied as a model system to study degradation processes in organic semiconductor devices due to its extensive knowledge base. Photoluminescence spectroscopy (PL) is a useful tool in understanding the stability of P3HT, as the emission spectrum corresponds to various morphological and structural transitions in P3HT. We observed exponential decay of PL intensity with humidity accelerated degradation under dark conditions, and with light induced degradation during high illumination. Additionally, we observed changes in the shape of PL peak under various degradation conditions. To investigate the shape changes, we performed a peak deconvolution to analyze particularly the effect of light degradation on the different emission peaks of P3HT. We additionally found that nanoparticle interlayers can change the degradation properties of P3HT thin films, particularly in high humidity conditions. These results contribute to better understanding of the physical degradation mechanisms present in P3HT and provide guidance for necessary precautions during laser exposure for future degradation measurements. Figure 1