Suppressing the Dark Current While Improving the Quantum Efficiency in Shortwave Infrared Organic Photodetectors Through Naphthalenediimide-Based Interlayer

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.