Switchable NIR to Visible Organic Photodetector

Science Magazine publishes a paper "Near-infrared and visible light dual-mode organic photodetectors" by Zhaojue Lan, Yanlian Lei, Wing Kin Edward Chan, Shuming Chen, Dan Luo, and Furong Zhu from Hong Kong Baptist University and Southern University of Science and Technology, Shenzhen, China.

"We report a dual-mode organic photodetector (OPD) that has a trilayer visible light absorber/optical spacer/near-infrared (NIR) light absorber configuration. In the presence of NIR light, photocurrent is produced in the NIR light–absorbing layer due to the trap-assisted charge injection at the organic/cathode interface at a reverse bias. In the presence of visible light, photocurrent is produced in the visible light–absorbing layer, enabled by the trap-assisted charge injection at the anode/organic interface at a forward bias. A high responsivity of higher than 10 A/W is obtained in both short and long wavelengths. The dual-mode OPD exhibits an NIR light response operated at a reverse bias and a visible light response operated at a forward bias, with a high specific detectivity of ~10^13 Jones in both NIR and visible light ranges. A bias-switchable spectral response OPD offers an attractive option for applications in environmental pollution detection, bioimaging process, wellness, and security monitoring in two distinct bands."