Sensitive near-infrared circularly polarized light detection via non-fullerene acceptor blends

Circularly polarized light (CPL) is widely used for various applications in sensing and imaging^1–3. An ongoing challenge is to realize high-quality CPL detection using chiral organic semiconductors, especially in the near-infrared (NIR) region⁴. Chiral molecules tend to rely on twisted stereogenic moieties; however, conventional approaches to reduce the bandgap of organic semiconductors are based on the use of co-planar backbones that commonly lead to molecular symmetries preventing chirality. Here we report a widely applicable strategy to directly induce chiroptical activity in planar non-fullerene acceptors^5–7, which are widely used for high-performance organic photovoltaics and provide a wealth of opportunities to fill the spectral gap of CPL detection in the NIR regime. We demonstrate proof-of-concept circularly polarized organic photodiodes using chiroptically active non-fullerene acceptor blends, which exhibit strong circular dichroism and hence great sensitivity to CPL in the NIR region. Importantly, this strategy is found to be effective in a wide series of state-of-the-art non-fullerene acceptor families including ITIC⁵, o-IDTBR⁶ and Y6 analogues⁷, which substantially broadens the range of materials applicable to NIR CPL detection.