Non‐Resonant Barrier Excitation in Conjugated Aromatic Ligand‐Modified Perovskite Quantum Dots Enables a High Quantum Efficiency
Hang Yin, Qing Yang, Tianxin Bai, Honglei Wang, Bin Yang, Qinhua Wei, Yingnan Wu, Ruiling Zhang, Laishun Qin, Junsheng Chen, Feng Liu, Jianyong Liu, Keli Han
Abstract
Abstract CsPbI 3 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 CsPbI 3 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 (H 2 TPP)‐modified CsPbI 3 QDs is presented, which enables a high PLQY in the high‐energy excitation regime as well as enhanced phase stability. Particularly, the proposed H 2 TPP ligand possesses adequate energy depth needed to realize NRBE in CsPbI 3 QDs, which allows efficient charge injection from organic ligands to the inorganic core. As a result, the H 2 TPP‐modified CsPbI 3 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.