Large-area black phosphorus/perylene-3,4,9,10-tetracarboxylic dianhydride surface charge transfer doped flexible photodetector

Flexible photodetectors have garnered significant research attention owing to their enormous application prospects in various emerging fields, such as flexible electronics, stretchable devices, implantable systems, portable devices, wearable technology, and optoelectronics. Black phosphorus (BP) with its high carrier mobility and layer-dependent bandgap tunability (0.3–2.0 eV) has emerged as a promising candidate material in the field of flexible optoelectronics. However, the preparation of BP films typically requires high-temperature and high-pressure conditions, which are often accompanied by expensive equipment, limiting their application in optoelectronics. In this study, a rapid and scalable liquid-phase interface assembly method for preparing large-area BP films is presented. Uniform films approximately 20 nm thick were fabricated, and for the first time, discrete perylene-3,4,9,10-tetracarboxylic dianhydride grains were modified through post-annealing treatment to form an organic-inorganic interfacial charge transfer doping. The entire preparation process is compatible with most rigid and flexible substrates. The resulting flexible devices demonstrate spectral response spanning 450–1550 nm with 24 ms response time, achieving a responsivity of 2.21 mA/W at 1550 nm under 7.18 mW/cm² power density. This compatible strategy bridges the gap between high-performance BP photonics and practical flexible integration.