Tellurophene-Based Random Copolymers for High Responsivity and Detectivity Photodetectors

Abstract

Organic photodetectors (OPDs) have attracted great attention because of their advantages including tunable response range, easy processability, and flexibility. Various conjugated polymers have been developed for high-performing OPDs. Herein, a series of tellurophene-based random copolymers containing two typical electron-withdrawing units naphthalene diimide (NDI) and perylene diimide (PDI) are designed and synthesized. Through varying the ratio of PDI/NDI moieties of the analogous polymers, the optophysical properties and film morphology, together with photodetector performances, are systematically tuned. It was demonstrated that the photodetectors based on the polymer with the molar ratio of PDI/NDI units of 70/30 possessed strong photoinduced absorption and favorable morphology via transient absorption spectra and atomic force microscopy studies. As a result, a high responsivity about 19.1 A/W at 600 nm and an excellent detectivity more than 10 Jones ranging from 350 to 600 nm were successfully achieved, which are among the highest values for OPDs and comparable to inorganic counterparts.

Recent Progress on Photomultiplication Type Organic Photodetectors

“…An external voltage is applied to read out the photon‐derived carriers, and gain can be realized by multiple carrier recirculation. Since more than one electron can flow in consequence of a single absorbed photon, the EQE of >100% is possible, which means that an incident photon triggers an electrical current flow provided by numerous electrons …”

Phase Control Behavior of Lateral Polymer Photodetectors Using Strong Aggregation Bulk Heterojunction Film

“…In addition, the shot noise from the dark current as a major factor for the D * value is reported by much literature. [ 9 ] So, these parameters are calculated according to the following equations, [ 12,20,26 ] Here, J ph , J dark , hυ , and LI are the photocurrent density, dark current density, photon energy, and incident light intensity respectively; T is the transmission of light through the film (Table S1, Supporting Information) and q is the absolute value of electron charge.…”

“…[ 16,17 ] At present, there are many device physical approaches to improve the performance of BHJ photodetectors by changing the carrier injection mode, such as introducing a transport layer or a barrier layer and adjusting the energy level difference of asymmetric electrodes. [ 2,18–20 ] Besides, the intrinsic characteristics of materials including aggregation behavior or phase separation of polymers can also ultimately have a significant impact on the performance of polymer photodetectors. [ 21,22 ] However, the report received little advance on how to achieve phase control behavior in aggregated thin film devices and the way in which the carriers transfer.…”

The Synthesis and Optoelectronic Applications for Tellurophene‐Based Small Molecules and Polymers

“…[47] Through varying the molar ratio of PDI/NDI units, the physicochemical properties of the conjugated polymers were systematically investigated. [47] Through varying the molar ratio of PDI/NDI units, the physicochemical properties of the conjugated polymers were systematically investigated.…”

“…Huang's group further developed another series of tellurophene-based copolymers P18 containing both NDI and PDI units in 2018. [47] Through varying the molar ratio of PDI/NDI units, the physicochemical properties of the conjugated polymers were systematically investigated. It was found that the favorite ratio of PDI/NDI units in P18 was 70/30 for organic photodetectors (OPDs), and P18 based devices demonstrated a high responsivity of 19.1 A/W at 600 nm and more than 10 12 Jones detectivity from 350 to 600 nm, which was among the best performances of OPDs.…”