Ultrafast Charge Carrier Dynamics in InP/ZnSe/ZnS Core/Shell/Shell Quantum Dots
Shijia Zeng,
Zhenbo Li,
Wenjiang Tan,
Jinhai Si,
Yuren Li,
Xun Hou
Affiliations
Shijia Zeng
Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Shaanxi Key Laboratory of Information Photonic Technique, School of Electronics Science and Engineering, Xi’an Jiaotong University, 28 Xianning Road, Xi’an 710049, China
Zhenbo Li
Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Shaanxi Key Laboratory of Information Photonic Technique, School of Electronics Science and Engineering, Xi’an Jiaotong University, 28 Xianning Road, Xi’an 710049, China
Wenjiang Tan
Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Shaanxi Key Laboratory of Information Photonic Technique, School of Electronics Science and Engineering, Xi’an Jiaotong University, 28 Xianning Road, Xi’an 710049, China
Jinhai Si
Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Shaanxi Key Laboratory of Information Photonic Technique, School of Electronics Science and Engineering, Xi’an Jiaotong University, 28 Xianning Road, Xi’an 710049, China
Yuren Li
Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Shaanxi Key Laboratory of Information Photonic Technique, School of Electronics Science and Engineering, Xi’an Jiaotong University, 28 Xianning Road, Xi’an 710049, China
Xun Hou
Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Shaanxi Key Laboratory of Information Photonic Technique, School of Electronics Science and Engineering, Xi’an Jiaotong University, 28 Xianning Road, Xi’an 710049, China
The excellent performance of InP/ZnSe/ZnS core/shell/shell quantum dots (CSS-QDs) in light-emitting diodes benefits from the introduction of a ZnSe midshell. Understanding the changes of ultrafast carrier dynamics caused by the ZnSe midshell is important for their optoelectronic applications. Herein, we have compared the ultrafast carrier dynamics in CSS-QDs and InP/ZnS core/shell QDs (CS-QDs) using femtosecond transient absorption spectroscopy. The results show that the ZnSe midshell intensifies the electron delocalization and prolongs the in-band relaxation time of electrons from 238 fs to 350 fs, and that of holes from hundreds of femtoseconds to 1.6 ps. We also found that the trapping time caused by deep defects increased from 25.6 ps to 76 ps, and there were significantly reduced defect emissions in CSS-QDs. Moreover, the ZnSe midshell leads to a significantly increased density of higher-energy hole states above the valence band-edge, which may reduce the probability of Auger recombination caused by the positive trion. This work enhances our understanding of the excellent performance of the CSS-QDs applied to light-emitting diodes, and is likely to be helpful for the further optimization and design of optoelectronic devices based on the CSS-QDs.
