Intrinsic Linear Dichroism of Organic Single Crystals toward High‐Performance Polarization‐Sensitive Photodetectors

The ability to detect light in photodetectors is central to practical optoelectronic applications, which has been demonstrated in inorganic semiconductor devices. However, so far, the study of polarization-sensitive organic photodetectors, which have unique applications in flexible and wearable electronics, has not received much attention. Herein, the construction of polarization-sensitive photodetectors based on the single crystals of a superior optoelectronic organic semiconductor, 2,6-diphenyl anthracene (DPA), is demonstrated. The systematic characterization of two-dimensionally grown DPA crystals with various techniques definitely show their strong anisotropy in molecular vibration, optical reflectance and optical absorption. In terms of polarization sensitivity, DPA-crystal based photodetectors exhibit a linear dichroic ratio up to ≈1.9. Theoretical calculations confirm that intrinsic linear dichroism, originated from the anisotropic in-plane crystal structure, is responsible for the polarization sensitivity of DPA crystals. This work opens up a new door for exploiting organic semiconductors for developing highly compact polarization photodetectors and providing new functionalities in novel flexible optical and optoelectronic applications.