Light-Triggered Pyroelectric Nanogenerator Based on a pn-Junction for Self-Powered Near-Infrared Photosensing

Abstract

A nanogenerator, as a self-powered system, can operate without an external power supply for energy harvesting, signal processing, and active sensing. Here, near-infrared (NIR) photothermal triggered pyroelectric nanogenerators based on pn-junctions are demonstrated in a p-Si/n-ZnO nanowire (NW) heterostructure for self-powered NIR photosensing. The pyroelectric-polarization potential (pyro-potential) induced within wurtzite ZnO NWs couples with the built-in electric field of the pn-junction. At the moment of turning on or off the NIR illumination, external current flow is induced by the time-varying internal electric field of the pn-heterostructure, which enables a bias-free operation of the photodetectors (PDs). The NIR PD exhibits a high on/off photocurrent ratio up to 10 and a fast photoresponse component with a rise time of 15 μs and a fall time of 21 μs. This work provides an unconventional strategy to achieve active NIR sensing, which may find promising applications in biological imaging, optoelectronic communications, and optothermal detections.

Photocurrent Polarity Controlled by Light Wavelength in Self-Powered ZnO Nanowires/SnS Photodetector System

“…Normally, the design of self-powered photodetectors is based on either an integrated energy harvesting unit or an internal built-in electric field, which is necessary for separating the photo-generated charge pairs (electrons and holes) and thus forming photocurrent ( Peng et al., 2014 , Su et al., 2017 , Wang et al., 2015 , Choi et al., 2009 , Ouyang et al., 2017 , Chen et al., 2016 ). During the optoelectronic process, the direction of the photo-generated electric field is opposite to that of the built-in electric field, which can weaken the separation of charge carriers ( Wang et al., 2017 , Heeger, 2014 ). Up to now, the p-n junction and Schottky barrier have been widely utilized to enhance built-in electric fields ( Zhao et al., 2017 , Wu et al., 2016 , Peng et al., 2017 , Yu et al., 2017 , Zhang et al., 2012 , Xiang et al., 2015 , Wu and Wang, 2016 ).…”

Low‐dimensional nanomaterial/Si heterostructure‐based photodetectors

“…The key step in fabricating the flexible Si substrate was etching Si wafers with 50% potassium hydrate solution at 130 °C for several hours. Wurtzite ZnO or CdS have been integrated with the flexible Si substrate, where the pyroelectric‐polarization potential produced within nanowires coupled with the inner electric field of the p‐n junction performs very well. Both the photoresponsivity and detectivity with respect to the relative peak‐to‐peak current were improved.…”

Perylenediimide chromophore as an efficient photothermal agent for cancer therapy

“…Near-infrared (NIR, 650-900 nm) irradiation has attracted extensive attention as an efficient stimulus in PTT. NIR light can penetrate deep tissues to activate the exogenous photothermal agents efficiently in vivo, with little nonspecific thermal damage [11][12][13][14]. Thus, the investigation of photothermal agents is focused on improving their photothermal capability, photostability, and reducing their biotoxicity.…”