High-Performance Broad-Spectrum Photodetector by Suppressing Stray Electrons by Adopting a Hybrid CQD/Organic Architecture

Abstract

Broad-spectrum photodetectors (PDs) are essential for various health monitoring, night vision, and telecommunications applications, but their detectivity in a wide absorbance region is limited by undesirable electronic response properties. Colloidal quantum dots (CQDs) are a promising system for broad-spectrum detection, whereas their practical potential is hindered by suboptimal dark current characteristics. To overcome these challenges, we propose a layered architecture comprising CQDs and a bulk heterojunction (BHJ) organic film as a hole transport layer. The integration of PbS CQDs offers multiple benefits, including bandgap tuning for minimizing thermal carriers, surface passivation to reduce recombination rates, and the formation of high-quality interfaces with organic layers, which collectively contribute to suppressing dark current leakage and thermal excitations by suppressing stray electrons. By integrating ITIC into the BHJ film, the device detectability is significantly enhanced, reaching 10¹³ Jones in the 400–1000 nm spectral range. This improvement is attributed to the higher lowest unoccupied molecular orbital (LUMO) of ITIC molecules, which effectively hinders electron injection. Additionally, J-aggregation-induced molecular stacking and optimized phase separation of BHJ films contribute to the enhanced performance. The integration of diverse materials offers greater flexibility in device design and functionality, enabling the development of more advanced and sophisticated optoelectronic devices. Furthermore, this approach could significantly enhance the theoretical and practical understanding of optoelectronic device engineering, leading to the development of more advanced optoelectronic devices.