Intrinsic polarization-sensitive organic photodetector with self-assembled all-polymer heterojunction

X. Luo, Y. Xue, J. Wu, W. Cai, D. Täuber, I. Malovicho, B. Sava, G. Cen, X. Lu, C. Zhao, I. G. Scheblykin, J. Yu, W. Mai, F. Liu, E. Wang and L. Hou

Applied Physics Letters 121, 233301 (2022)
Intrinsic polarization-sensitive photodetectors (IPPDs) have attracted considerable attention in recent years due to their simplicity in configuration, making them ideal candidates for compact and integrated polarization-sensitive sensing and imaging systems. Photoactive films with intrinsic optical anisotropy are necessary for IPPDs. This study reports an achievement of photoactive films based on all-polymer heterojunction films with in-plane optical anisotropy using a simple bottom-up self-assembly method. Both the donor (TQ1) and acceptor (N2200) polymers have the same spatial orientation with distinct anisotropy, approaching a dichroic ratio (DR) of 8. Polarization-sensitive light absorption is due to the uniaxially oriented polymer chains, which are dominated by lamellar packing with edge-on orientation. For IPPDs based on this anisotropic all-polymer heterojunction film, a photocurrent anisotropy was found with a polarized photocurrent ratio of 2.6. The detectivity of these IPPDs was found to be 1.9 × 1011 Jones (@ ∼600 nm, 0 V bias). Our work shows that oriented polymer donor–acceptor films fabricated using bottom-up self-assembly have great potential in applications, such as polarization detection.