Non‐Resonant Barrier Excitation in Conjugated Aromatic Ligand‐Modified Perovskite Quantum Dots Enables a High Quantum Efficiency

Abstract

AbstractCsPbI3 quantum dots (QDs) hold tremendous promise for quantum emitters, but they undergo a considerable energy loss when excited above their optical bandgap, which impedes the utilization of high‐energy photons. Different surface modification strategies have been proposed to improve the phase stability of CsPbI3 QDs, however, little progress has been made to realize high photoluminescence quantum yield (PLQY) with high‐energy photon excitation. Here, a non‐resonant barrier excitation (NRBE) mechanism in conjugated aromatic tetraphenylporphyrin (H2TPP)‐modified CsPbI3 QDs is presented, which enables a high PLQY in the high‐energy excitation regime as well as enhanced phase stability. Particularly, the proposed H2TPP ligand possesses adequate energy depth needed to realize NRBE in CsPbI3 QDs, which allows efficient charge injection from organic ligands to the inorganic core. As a result, the H2TPP‐modified CsPbI3 QDs exhibit enhanced light absorption, large Stokes shift, and near‐unity red emission when excited above the optical bandgap. The findings provide new insights into the ligand design strategies for improving optoelectronic properties.