The impact of carrier transport confinement on the energy transfer between InGaN/GaN quantum-well nanorods and colloidal nanocrystals

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.