Dipole Field-Driven Organic-Inorganic Heterojunction for Highly Sensitive Ultraviolet Photodetector

Developing high-performance organic-inorganic ultraviolet (UV) photodetectors (PDs) has attracted considerable attention. However, this development has been hindered due to poor directional charge-transfer ratios in transport layers, excessive costs, and an ambiguous underlying mechanism. To tackle these challenges, we constructed a heterojunction of economic Mg-doped ZnO (MgZnO) nanorods and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) [PEDOT:PSS (P:P)] that utilizes dipole field-driven spontaneous polarization to enhance photogenerated charge kinetics. As a result, the proposed heterojunction has an improved noise equivalent power of 3.16 × 10^-11 W Hz^-1/2), a normalized detection rate (D*) of 8.96 × 10⁹ jones, and external quantum efficiency comparable to other ZnO-based devices. Notably, the prepared PDs showed a photocurrent of 4.8 × 10^-3 μA under a faint UV light having an intensity of 1 × 10^-5 W cm^-2, exceeding the performance of the most state-of-the-art ZnO-based UV sensors. The introduction of Mg into ZnO is responsible for the high performance, as it causes a lattice mismatch and distortion of the Mg-doped ZnO unit cell. It results in improved dipole movement and the creation of a dipole field, accelerating the directional electron-transfer process. Using a dipole field to manipulate the migration and transport of photogenerated carriers represents a promising approach for achieving outstanding performance in UV PDs.