Temperature-dependent photoluminescence in light-emitting diodes

Abstract

Temperature-dependent photoluminescence (TDPL), one of the most effective and powerful optical characterisation methods, is widely used to investigate carrier transport and localized states in semiconductor materials. Resonant excitation and non-resonant excitation are the two primary methods of researching this issue. In this study, the application ranges of the different excitation modes are confirmed by analysing the TDPL characteristics of GaN-based light-emitting diodes. For resonant excitation, the carriers are generated only in the quantum wells, and the TDPL features effectively reflect the intrinsic photoluminescence characteristics within the wells and offer certain advantages in characterising localized states and the quality of the wells. For non-resonant excitation, both the wells and barriers are excited, and the carriers that drift from the barriers can contribute to the luminescence under the driving force of the built-in field, which causes the existing equations to become inapplicable. Thus, non-resonant excitation is more suitable than resonant excitation for studying carrier transport dynamics and evaluating the internal quantum efficiency. The experimental technique described herein provides fundamental new insights into the selection of the most appropriate excitation mode for the experimental analysis of carrier transport and localized states in p-n junction devices.

Role of Localized States in Photoluminescence Dynamics of High Optical Gain CsPbBr3 Nanocrystals

“…As the temperature increases, the PL intensity decreases with a simultaneous blue shift of the emission peak. [32] Figure 3a shows the Arrhenius plot of integrated PL intensity versus inverse temperature, fitted using the Arrhenius equation as below [33,34] [29] The room-temperature forward PL yield (η PL_forward ) [30] of the CsPbBr 3 NC film ≈31% at the excitation energy ≈3.7 µJ cm −2 .…”

Surface State‐Induced Anomalous Negative Thermal Quenching of Multiferroic BiFeO3 Nanowires

“…On the contrary, the carriers associated with higher activation energy will gain sufficient energy at higher temperatures, the temperature change affects this emission much more. Thus the non‐radiative relaxation process with a small activation energy of E1, E3, E4 results in a decrease in the PL intensity . Therefore, as the temperature is increased, the carriers with lower activation energy will start to escape into the barrier where they can recombine non‐radiatively leading to decrease in the PL intensity, while carriers with higher activation energy lead to NTQ behavior.…”

Piezo‐Phototronic Effect Controlled Dual‐Channel Visible light Communication (PVLC) Using InGaN/GaN Multiquantum Well Nanopillars

“…Likewise, more carriers generated in GaN barrier layers are trapped by localized states, impurities, or defects or rapidly recombine. However, the excitation rate in GaN barrier layer is much lower than the localized emission in InGaN quantum well and thus the contribution of GaN barrier layer to the emission of InGaN quantum‐well layer could be ignored, which has been proved in our previous work . Figure a shows the PL spectrum of MQWs nanopillar structure under no force at an excitation power of 45 mW.…”