Insight into degradation mechanisms of bulk heterojunction organic solar cells

Bulk heterojunction organic solar cells (BHJ OSCs) potentially can offer low cost, large area, flexible, light-weight, clean, and quiet alternative energy sources for indoor and outdoor applications. OSCs using non-fullerene acceptors (NFAs) have garnered a lot of attention during the past few years and shown dramatic increases in the power conversion efficiency (PCE). PCEs higher than 19% for single-junction systems have been achieved, but the device lifetime is still too short for practical applications. Thus, understanding the degradation mechanisms in an OSC is crucial to improve its long-term stability. In this talk, I will discuss the degradation mechanisms in BHJ OSCs. We investigated the impact of different blend materials and device structures on the device stability. A combination of characterization methods such as solid state Nuclear Magnetic Resonance (NMR), resonant soft X-ray scattering (RSoXS), AFM, X-ray photoelectron spectroscopy (XPS), Electron paramagnetic resonance (EPR) spectroscopy, and capacitance spectroscopy are employed to gain insight into the device degradation mechanisms. We propose strategies to improve the device stability.