High-sensitivity, fast-response and broad-spectral photodetector based on Lead-free Cs₂AgBiBr₆/organic Heterjunction

Lead-free perovskite Cs₂AgBiBr₆ has emerged as a promising material for constructing stable and environmentally friendly photodetectors (PDs), owing to its excellent stability, non-toxicity, and solution-processability. However, current PDs based on Cs₂AgBiBr₆ are limited by their operational bandwidth, with spectral detection typically restricted to wavelengths below 700 nm. In this work, we report the successful integration of Cs₂AgBiBr₆ with an organic heterojunction, resulting in a broadband, high-sensitivity, and fast-response PD that exhibits a remarkable spectral response extending up to 1208 nm. Under a bias voltage of -0.3 V, the external quantum efficiencies at 730 nm and 850 nm reached 93% and 78%, respectively. Furthermore, at a wavelength of 850 nm, the device demonstrated a responsivity of 0.53 A/W and a detectivity of 4.85 × 10¹² Jones. The response time was recorded at an impressive 548 ns at 532 nm. Additionally, the functionality of the device was successfully demonstrated in the detection of photoplethysmography signals, showcasing its practical applicability. This research offers a promising pathway toward the advancement of cost-effective, broadband, and high-performance PDs.