Semi‐Transparent, Chiral Organic Photodiodes with Incident Direction‐Dependent Selectivity for Circularly Polarized Light

Abstract Detection of the circular polarization of light is possible using chiral semiconductors, yet the mechanisms remain poorly understood. Semi‐transparent chiral photodiodes allow for a simple experiment to investigate the basis of their selectivity: changing the side from which the diode is illuminated. A reversal of circular selectivity is observed in photocurrent generation when changing the direction of illumination on organic, bulk‐heterojunction cells. The change in selectivity can be explained by a space‐charge limitation on the collection of photocarriers in combination with preferential absorption of one of the circular polarizations of near‐infrared light by the chiral non‐fullerene acceptor. The space‐charge limitation is supported by detailed measurements of frequency and intensity dependence of dc and ac photocurrents.