The Impact of Carrier Transport Confinement on the Energy Transfer Between InGaN/GaN Quantum-Well Nanorods and Colloidal Nanocrystals.

Min. Bin Jiang1, Chunfeng Zhang1,*,  Xiaoyong Wang1,Min Joo Park2,Joon Seop Kwak2,*,Jian Xu3,Huichao Zhang4,Jiayu Zhang4,Fei Xue1,Min Xiao5,6.

Advanced Functional Materials vol. 22 issue 15 August 7, 2012. p. 3146-3152

1. National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
2. Department of Printed Electronic Engineering, Sunchon National University, Sunchon, Jeonnam 540-742, Korea
3. Department of Engineering Science and Mechanics, Penn State University, University Park, PA 16802, USA
4. Advanced Photonic Center, Southeast University, Nanjing 210096, China
5. National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
6. Department of Physics, University of Arkansas, Fayetteville, AR 72701, USA

 

Abstract

The energy transfer (ET) between InGaN/GaN multiple-quantum-well (MQW) nanorods (NRs) and semiconductor nanocrystals (NCs) for efficient color conversion is studied. An exceptional contribution of carrier transport confinement to the ET mechanisms is observed in the proximal side-wall coupling system, which consists of InGaN/GaN NRs and CdSe NCs. Under relatively low or high excitation, the ET rate shows different carrier-density dependence, resulting from different electron-hole configurations, i.e., bound excitons and free carriers. In the localized exciton regime, the ET rate decreases when increasing temperature from 20 K to 200 K. However, in the free-carrier regime, the ET rate varies insignificantly in the same temperature range. The temperature dependence in this NR-NC coupling system is different from that in the previously studied planar MQW-NC coupling system. It is suggested that the carrier transport confinement in NRs is a major factor for these divergences. The highly efficient ET with efficiency up to 80% shows a promising potential of using such NR-NC coupled structures for ET-pumped, NC-based, light-emitting devices.

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Additional Information

Nonradiative energy transfer from InGaN/GaN quantum-wells to semiconductor nanocrystals can be employed to improve the effiicency of color conversion in white LED technology. A team led by Xiao have investigated the mechanisms of energy transfer in a proximal side-wall coupling system which consists of InGaN/GaN quantum-well nanaorods and CdSe nanocrystals. In the temperature-dependent ultrafast spectroscopic study, the configurations of electron-hole pairs and the confinement of carrier diffusion have been observed to be key factors that govern the energy transfer. With these knowledge, the optimized efficiency of energy transfer approachs to ~ 80 %, evidencing a promising potential in the hybrid nano-structures for white LED applications.