Dual-Band, Efficient Self-Powered Organic Photodetectors with Isotype Subphthalocyanine-Based Heterojunctions toward Secure Optical Communications

Baofa Lan; Xiaoming Wu; Feng Ma; Lei Zhang; Shougen Yin

doi:10.1021/acsami.2c09008

Dual-Band, Efficient Self-Powered Organic Photodetectors with Isotype Subphthalocyanine-Based Heterojunctions toward Secure Optical Communications

ACS Appl Mater Interfaces. 2022 Sep 21;14(37):42277-42288. doi: 10.1021/acsami.2c09008. Epub 2022 Sep 8.

Authors

Baofa Lan¹, Xiaoming Wu¹, Feng Ma², Lei Zhang³, Shougen Yin¹

Affiliations

¹ Key Laboratory of Display Materials and Photoelectric Devices, Tianjin Key Laboratory of Photoelectric Materials and Devices, National Demonstration Center for Experimental Function Materials Education, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, P. R. China.
² Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion, School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384, P. R. China.
³ School of Science, Tianjin Chengjian University, Tianjin 300384, P. R. China.

PMID: 36074059
DOI: 10.1021/acsami.2c09008

Abstract

High-performance heterojunction organic photodetectors (OPDs) are of great significance in optical detecting technology due to their tailorable optoelectronic properties. Herein, we designed and synthesized three n-type subphthalocyanine (SubPc) derivatives PhO-BSubPcF₁₂, CHO-PhO-BSubPcF₁₂, and NO₂-PhO-BSubPcF₁₂ via axial nonhalogen substitution on fluorinated SubPc. These SubPc derivatives exhibit improved intramolecular charge transfer, high electron mobilities, optimized energy levels, and good thermal stability. The novel isotype p-n SubPc heterojunctions are evaluated as photosensitive layers in OPDs, which show a UV-visible dual-band response and self-powered effect. The optimal OPD with Br-BSubPc/NO₂-PhO-BSubPcF₁₂ presents stable and superior performances with a high responsivity (R) of 0.14 A W^-1, a peak external quantum efficiency (EQE) of 30.6%, and an extremely low dark current of 0.92 nA cm^-2 under a 570-595 nm illumination without a bias voltage. It has outperformed most of the reported SubPc-based OPDs. The better interfacial contact of p-n SubPc derivatives leads to a large depletion region with decreased trap densities as well as a low carrier recombination rate, which is conducive to the photoinduced carriers' separation and well-balanced transport, resulting in high device performances. Moreover, a secure communication strategy is successfully demonstrated by dual-band optimal OPD. This work is expected to provide some guidance for molecular engineering and device performance toward multifunctional electronics.

Keywords: SubPc-based heterojunctions; dual-band OPD; energy level manipulation; intramolecular charge transfer; low dark current; n-type SubPc derivatives.