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

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.

Bidirectional and Dual‐Mode Organic Photodetector Enables Secure Ultraviolet Communication

“…[9,[23][24][25][26] However, it remains a challenge in developing a photodetector with dual-band response. Previous solutions usually focused on the multi-stacked photosensitive layers (heterojunction stacking or single semiconductor stacking), dependent on the photosensitive layers with different spectral response band to realize dual-band response in a single photodetector, [27][28][29][30][31] further, most of them required assistant of bidirectional charge injection. Moreover, spectral matching and interfaces contacting in the multi-stacked structure complex the device fabrication process.…”

High-Performance Ultraviolet Photodetector Based on Single-Crystal Integrated Self-Supporting 4H-SiC Nanohole Arrays

“…In addition, the linear dynamic range (LDR), which is an advantage value of the PDs and represents a strong range of light intensity with a constant response rate, is another index to evaluate the PDs. This parameter can be defined as follows normalL normalD normalR .25em ( d B ) = 20 log nobreak0em.25em⁡ I normalp normalh I normald normala normalr normalk …”

“…Meanwhile, Figure 4d,e reveals that the highest detectivity (D*) and EQE of the device are 6 × 10 10 Jones and 273%, which are comparable to or even better than the previous reported 4H-SiC-based PDs (as summarized shown in Table 1). In addition, the linear dynamic range (LDR), which is an advantage value of the PDs and represents a strong range of light intensity with a constant response rate, 40 is another index to evaluate the This parameter can be defined as follows 41 = I I LDR (dB) 20log ph dark (8) Figure 4f shows the LDR curve of the SiC PD exposed to different light intensities. It is observed that the LDR of the PD is responsive over a wide range of light intensities and gradually increases as the light intensity increases, and it reaches a maximum value of 48 dB at 35.60 mW/cm 2 .…”

Vacuum-deposited organic photodetectors utilizing non-fullerene acceptors for enhanced detectivity in the green visible light spectrum

“…However, the resulting device showed low performance with an EQE value of 10.9% and a detectivity of 5 Â 10 10 Jones at a bias voltage of 0 V. 39 Lan et al used a PHJ of the Br-BSubPc/NO 2 -PhO-BSubPcF 12 layer, which can achieve a low dark current density of 9.2 Â 10 À10 A cm À2 but a low EQE of 30.6% at a bias voltage of 0 V. Thus, the detectivity at a wavelength of 570 nm shows the value of 8.19 Â 10 12 Jones. 40 Shen et al demonstrated that PHJ organic photodetectors based on the fullerene acceptor using SubPc/C 60 as an active layer can achieve an EQE of 40.6% and a dark current density of 1.2 Â 10 À7 A cm À2 , which results in detectivity with a value of 1.7 Â 10 À11 Jones. 41 Regardless of limitations in exciton diffusion length, BHJ shows a charge-trapping effect and efficient exciton dissociation.…”