Highly Efficient Ternary Near-Infrared Organic Photodetectors for Biometric Monitoring

Abstract

Near-infrared (NIR) small-molecule acceptors that absorb at wavelengths of up to 1000 nm are attractive for applications in organic photodetectors (OPDs) and biometrics. In this study, we incorporated IEICO-4F as the third component for PffBT4T-2OD:PC 71 BM-based OPDs to provide an efficient NIR response while greatly suppressing the leakage current at reverse bias. By varying the blend ratio and thickness (250−600 nm), we obtained an NIR OPD displaying an ultralow dark-current density (J D = 2.62 nA cm −2 ), ultrahigh detectivity [D* = 7.2 × 10 12 Jones (850 nm)], high sensitivity, and photoresponsivity covering the region from the ultraviolet to the NIR. We used tapping-mode atomic force microscopy, optical microscopy, grazing-incidence wide-angle X-ray scattering, and contact angle measurements to investigate the effect of IEICO-4F on the performance of the ternary OPDs. The low compatibility of PffBT4T-2OD and IEICO-4F, originating from weak intermolecular interactions, allowed us to manipulate the degree of phase separation between the donor and acceptor in the ternary blends, leading to an optimized blend morphology featuring efficient charge separation, transport, and collection. To demonstrate its applicability, we integrated our OPD with two light-emitting diodes and used the system for precisely calculated transmissive pulse oximetry.

Customizable Organic Charge-Transfer Cocrystals for the Dual-Mode Optoelectronics in the NIR (II) Window

“…Through comparison, it is found that these BF X TQ-based optoelectronic devices can achieve both photodetection and emission in the NIR (II) region, which exhibits comparable or superior properties to previously reported organic semiconductor devices with single optoelectronic functionalities in terms of wavelength or performance. For the photodetectors, the detectivity at 1064 nm can reach 1.76 × 10 14 Jone, which is comparable to some NIR photodetector properties (Figure a). ,,,− In addition, rod-shaped cocrystals can be fabricated as optical waveguide devices to realize a low optical-loss coefficient of 0.0097 dB/μm at 950 nm. This excellent optical performance is comparable to the previous studies in both the visible and NIR regions, showing superior photon transmission characteristics, which contributes to the highly promising applications in the field of photonics information technology (Figure b). ,,− …”

Flexible Broadband Organic Photodetectors with Ternary Planar-Mixed Heterojunction Semiconductors and Solution-Processed Polymeric Electrode

“…Under the assumption that shot noise predominantly governs the total noise, the D * could be simplified. This shot-noise-limited D * should be determined using the following equation: D * = R A B i normaln true≅ R A B i normals normalh normalo normalt true= R 2 q J normald …”

Improved performance of ZnO based inverted organic photodetectors with morphological and interfacial modification

“…Therefore, the noise spectrum density ( S n ) of different devices was measured to calculate D * under −0.1 V bias by the low frequency noise test system. The specific detectivity was calculated using the following equation, 66–68 where A is the effective area of OPD, B is the normalized bandwidth (1 Hz), and S n is the noise spectrum density in A Hz −1/2 .…”