Efficient Magnetism Controlled by Visible Light Using Perovskite Quantum Dots with Hybrid Interface Architecture

Spintronic devices represent a promising advancement in information storage, sensors, RF/microwave tunable devices, and other applications. Recently, researchers have developed a novel approach to energy‐efficiently manipulate spin states using photovoltaic (PV) thin‐film. However, optimization strategies for this method are relatively scarce. Here, a PV/magnetic thin film heterojunction featuring a perovskite quantum dots (PQDs) composite layer is presented with a hybrid interfacial architecture consisting of PCBM/PCBM@CsPbI₃ QDs/CsPbI₃ QDs/ PTB7‐Th heterojunction. The heterostructure facilitates more injection of photoelectrons into the ferromagnetic layer through an energy cascade mechanism model, resulting in greater magnetic changes compared to the PTB7‐Th: PC₇₁ BM system. Under 100 mW cm⁻² sunlight illumination, the out‐of‐plane ferromagnetic resonance shift increases by 626% (from −19 to −138 Oe), owing to improved photo‐induced electron doping. Additionally, the fluctuation of saturation magnetization (M_S) is magnified by 200% (from 9% to 27%) as well. These findings demonstrate that the efficient photovoltaic layer plays a critical role in optimizing magnetic manipulation and lays the groundwork for the next generation of solar‐driven spintronic devices.