Search

The significance of shortwave infrared (SWIR) photodetectors spans across various applications. Nevertheless, the limited spectral response of silicon‐based photodetectors and the high cost associated with materials like germanium (Ge) have impeded the widespread adoption of SWIR sensors, particularly in the realm of consumer electronics. This study explores the transformative impact of incorporating a cross‐linkable naphthalenediimide (c‐NDI) as both an electron transporting layer and a hole blocking layer in organic photodetectors (OPDs). The introduction of c‐NDI as an interlayer leads to substantial enhancements in SWIR OPD performance, particularly in terms of reducing dark current and augmenting external quantum efficiency. These improvements are most notable in ultra‐narrow bandgap SWIR systems, where c‐NDI demonstrates superior hole‐blocking capabilities. Besides, OPDs with c‐NDI interlayers also exhibit exceptional stability over time when compared to OPDs based on zinc oxide interlayer, underscoring c‐NDI's versatility as an interlayer. Most importantly, when compared to a commercially available Ge photodetector, c‐NDI‐based OPD demonstrates competitive detectivity, achieving 2.67 × 1011 Jones at a wavelength of 1300 nm. This performance even surpasses that of the Ge photodetector, highlighting the substantial potential of OPDs for SWIR imaging applications. [ABSTRACT FROM AUTHOR]

Organic photodetectors (OPDs) with spectral response extending from ultraviolet to near‐infrared domains are of great interest for many applications. Morphological impact on the performance of photomultiplication (PM)‐type OPDs, however, is still rarely investigated so far. Herein, a non‐fullerene acceptor, Y6‐Se‐HD, is synthesized, in which heavier selenium atoms substitute the sulfur atoms in the core of Y6, and used for fabricating PM‐OPDs. The resulting devices exhibit remarkable PM effects in a very broadband spectral range covering from 320 to 1090 nm. A maximum EQE value of ≈6500% at 860 nm is achieved at a low bias of −1.0 V. As compared with the device prepared with Y6 molecules, the Y6‐Se‐HD OPDs exhibited much enhanced performance. From the morphological analysis, we infer that Y6‐Se‐HD almost covers the entire active layer and avoids the direct contact of the hole‐trapping donor polymers with the Ag electrode, thereby resulting in stronger charge trapping and preventing possible charge recombination and/or quenching. Furthermore, finer phase separation between the donor and acceptor molecules also facilitates hole trapping and strengthens the PM effects. This research highlights the importance of morphological effects on the PM‐OPDs and demonstrates one approach for controlling the device morphology. [ABSTRACT FROM AUTHOR]

Shortwave infrared (SWIR) image sensors have unique functions in many optical applications, leading to widespread attention in developing next‐generation materials and photodetector technologies. Organic photodetectors (OPDs) are highly promising due to their flexibility in molecular design and processability. However, integrating OPDs with silicon readout integrated circuits (ROICs) poses numerous challenges, often resulting in underestimated device performance and limiting technological progress. To address the requirements of integrating top‐illuminated OPD with ROICs and to enhance the external quantum efficiency (EQE), optical microcavities are introduced into the OPDs. The EQE in the SWIR region can be effectively enhanced by properly adjusting the thicknesses of the photoactive layer (PAL) and interlayers. Simulations of the optical field distribution further support the active functions of the microcavity structure. The spatial variation of the microcavities allows the spectral response to shift from 1000 to 1400 nm, and the optimized device achieves an EQE of 25.8% at 1260 nm. Finally, the OPDs are integrated with a silicon‐based test kit, and the results reveal comparable sensing performance, demonstrating the high potential of microcavity resonance for device integration. This design effectively improves the integration of OPDs with traditional ROICs and advances SWIR‐based organic image sensor technology further toward commercialization. [ABSTRACT FROM AUTHOR]