不同波長發光體同時表面電漿子耦合以增強光色轉換效率

Abstract

在本論文研究中，我們放置銀奈米顆粒於發綠光的氮化銦鎵/氮化鎵量子井和發紅光的硒化鎘/硫化鋅量子點之間來同時與量子井和量子點產生表面電漿子耦合，以增強量子井和量子點的內部量子效率。我們也觀察到在塗佈高密度量子點樣品中，經由表面電漿子耦合量子點的絕對發光強度明顯增強。比較不同尺寸銀奈米顆粒所產生不同共振波長局域表面電漿子的耦合效果，我們發現當共振波長位於量子井和量子點發光波長中間時，量子點的內部量子效率提升最顯著。此現象是因為局域表面電漿子共振的涵蓋範圍包含了量子井和量子點的發光波段，表面電漿子耦合的效果不只分別增加了量子井和量子點的發光效率，也增強了量子點在量子井發光波段的吸收，結合上述因素可造成最佳量子點內部量子效率的提升。

By placing Ag nanoparticles (NPs) between green-emitting (~520 nm) InGaN/GaN quantum wells (QWs) and red-emitting (~620 nm) CdSe/ZnS quantum dots (QDs) for inducing simultaneous surface plasmon (SP) coupling with QWs and QDs, the internal quantum efficiencies (IQEs) of both QDs and QWs can be enhanced. With a high enough QD density, the absolute emission intensity of QDs can also be enhanced through SP coupling. By comparing the samples with different Ag NP geometries, an Ag NP structure producing the localized surface plasmon (LSP) resonance peak around the middle between the QW and QD emission wavelengths leads to the maximum QD IQE enhancement. This behavior is attributed to the LSP resonance coverage of both QW and QD emission wavelengths such that the SP coupling can be effective for enhancing QW emission at ~520 nm, QD absorption at ~520 nm, and QD emission at ~620 nm at the same time. The combination of those effects results in an overall largest increase of QD IQE.