The modulation of energy band alignment (EBA) of semiconductor heterostructure (HS) is challenging research to study excitons and future applications.  Korean researchers at Korea University and Sungkyunkwan University report the far-red interlayer excitons (IXs) emission from the HS of perovskite MAPbI3 and CdSe-ZnS-quantum dot (QD).  The study appears in the Advanced Science in March, 2023.

IXs formed at the interface of HSs have exhibited distinctive light emission characteristics, including long lifetime, spin and valley dependency, and gate-field modulation, which provide a promising platform for advanced excitonic devices including quantum information processing. Profs. Jinsoo Joo, Jeongyong Kim, and their research members fabricated new MAPbI3/CdSe-ZnS-QD HSs through EBA engineering and observed the far-red IXs at 873 nm at 3 K.

The lifetime of far-red IXs from the MAPbI3/CdSe-ZnS-QD HS was estimated to be 5.68 μs, which was ultra-longer (7950 times) than that of the pristine CdSe-ZnS-QD. The dipole direction of far-red IXs of MAPbI3/CdSe-ZnS-QD HS obtained from the back focal plane mapping images was strongly out-of-plane and clearly distinguishable from those of the intralayer excitons (MAPbI3 and CdSe-ZnS-QD).

Prof. Joo said that “We observed for the first time the emissive IXs in far-red region (700 – 900 nm) with long lifetime. We also realized the MAPbI3/CdSe-ZnS-QD HS photodetectors with increasing photocurrent and detectivity compared to the pristine MAPbI3 photodetectors at IX excitation.” “These findings will help to understand intrinsic characteristics of distinctive exciton species for semdiconductor HSs, which can apply to future photonics, optoelectronics, displays, quantum information, infrared health-care, bio-imaging, etc.”, Prof. Joo said.

Figure 1. (a) Schematic illustration of MAPbI3/CdSe-ZnS-QD heterostructure (HS). (b) Photoluminescence spectra of the MAPbI3/CdSe-ZnS-QD HS (black curve) and the far-red IX related signal (red dashed curve). (c) Current-voltage (I-V) curve of the MAPbI3-based photodetectors.

[Reference] T. J. Kim et al., (2023) “Far-Red Interlayer Excitons of Perovskite/Quantum-Dot Heterostructures” Advanced Science, DOI: 10.1002/advs.202207653

[Main Authors] Taek Joon Kim and Jinsoo Joo (Korea University), Jeongyong Kim (Sungkyunkwan University) 

* Contact email : Professor Jinsoo Joo (jjoo@korea.ac.kr)