Far-Red Interlayer Excitons of Perovskite/Quantum-Dot Heterostructures
Taek Joon Kim1, Sang-Hun Lee1, Eunji Lee2
1Department of Physics, Korea University, Seoul, 02841, Republic of Korea.
Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
|March 20, 2023
Summary
Interlayer excitons (IXs) in perovskite/quantum dot heterostructures exhibit long lifetimes and unique optical properties. Modulating quantum dot size tunes energy band alignment, enhancing IX emission and photodetector performance.
Area of Science:
- Materials Science
- Quantum Physics
- Optoelectronics
Background:
- Interlayer excitons (IXs) are quasiparticles formed at heterostructure interfaces with staggered band alignment.
- These IXs possess unique light-emitting and long-lifetime characteristics.
Purpose of the Study:
- To investigate the energy band alignments (EBAs) of MAPbI3/CdSe-ZnS quantum dot (QD) heterostructures.
- To modulate IX properties by varying QD diameters and explore their potential in optoelectronic devices.
Main Methods:
- Fabrication of heterostructures using MAPbI3 perovskite and CdSe-ZnS core-shell QDs of varying diameters.
- Photoluminescence (PL) spectroscopy to analyze emission characteristics and lifetimes.
- Back focal plane imaging to determine exciton dipole orientations.
Main Results:
- Observed far-red IX emission at 1.42 eV (645 nm) in type-II EBAs due to charge transfer.
- Achieved a significantly longer IX lifetime (5.68 µs) compared to intralayer excitons (0.715 ns).
- Demonstrated blue-shifting of PL peaks and linear intensity increase with excitation power, indicating strong dipole alignment.
Conclusions:
- Tuning QD size effectively modulates EBAs and enhances IX emission in MAPbI3/QD heterostructures.
- IXs exhibit distinct out-of-plane dipole orientations compared to intralayer excitons.
- Heterostructure photodetectors show improved photocurrent and detectivity under IX excitation, with notable behavior near MAPbI3's phase transition.
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