Solvent‐Mediated Growth of a Hierarchical Zero‐Dimensional Architecture for Efficient CsPbI ₃ Quantum Dot Solar Cells

Abstract Perovskite quantum dots (QDs) are promising optoelectronic materials. The large surface area provides an opportunity for ligand engineering to protect the QDs, while also impeding the charge transport in the QD array. Here, the solvent‐mediated growth of a hierarchical zero‐dimensional (HZD) architecture between CsPbI ₃ QDs is reported. The HZD architecture is grown on the CsPbI ₃ QD film through a feasible method rather than introducing intricate molecules into the CsPbI ₃ QD solution. Acetonitrile solvent with high polarity strips lead iodide from the QD surface, and then the lead iodide reacts with the phenethylamine iodide to form HZD architecture. The HZD architecture acts as a “charge bridge” to enhance the coupling between CsPbI ₃ QDs, resulting in improved photoelectric properties. As a result, the optimized device achieves a high‐power conversion efficiency of 15.4%, remarkably higher than the 14% of the control device. This work demonstrates the significance of surface chemistry for perovskite QDs and provides a feasible strategy for realizing high‐performance perovskite QDs‐based optoelectronic devices.