Full text of a new publication “Efficiency of True-Green Light Emitting Diodes: Non-Uniformity and Temperature Effects” by Ilya E. Titkov, Sergey Yu. Karpov (STR Group), Amit Yadav, Denis Mamedov, Vera L. Zerova and Edik Rafailov*, Materials 2017, 10(11), 1323; doi: 10.3390/ma10111323 is now available online.
Abstract: EQE of industrial-grade green InGaN LEDs has been measured in a wide range of operating currents at various temperatures from 13 K to 300 K. Unlike blue LEDs, the efficiency as a function of current is found to have a multi-peak character, which could not be fitted by a simple ABC-model. This observation correlated with splitting of LED emission spectra into two peaks at certain currents. The characterization data are interpreted in terms of non-uniformity of the LED active region, which is tentatively attributed to extended defects like V-pits. We suggest a new approach to evaluation of temperature-dependent light extraction and internal quantum efficiencies taking into account the active region non-uniformity. As a result, the temperature dependence of light extraction and internal quantum efficiencies have been evaluated in the temperature range mentioned above and compared with those of blue LEDs.
This work was supported by European Union FP7, NEWLED project. I.E.T. designed and performed the experiments and contributed to the manuscript preparation; S.Y.K. developed the paper concept, analytical model, and largely contributed to the manuscript preparation; D.M. contributed to the spectral data evaluation; A.Y. and V.L.Z. contributed to the experiment, scientific discussion, and manuscript preparation; E.R. supervised the project.