Quantitative electrochemical control over optical gain in colloidal quantum-dot and quantum-well solids

Jaco J. Geuchies; Baldur Brynjarsson; Gianluca Grimaldi; Indy Du Fossé; Robbert Dijkhuizen; Marijn Koel; Solrun Gudjonsdottir; Ward van der Stam; Wiel H. Evers; Pieter Geiregat; Zeger Hens; Arjan J. Houtepen

doi:10.1117/12.2569413

20 August 2020 Quantitative electrochemical control over optical gain in colloidal quantum-dot and quantum-well solids

Jaco J. Geuchies, Baldur Brynjarsson, Gianluca Grimaldi, Indy Du Fossé, Robbert Dijkhuizen, Marijn Koel, Solrun Gudjonsdottir, Ward van der Stam, Wiel H. Evers, Pieter Geiregat, Zeger Hens, Arjan J. Houtepen

Author Affiliations +

Proceedings Volume 11464, Physical Chemistry of Semiconductor Materials and Interfaces XIX; 114640R (2020) https://doi.org/10.1117/12.2569413
Event: SPIE Nanoscience + Engineering, 2020, Online Only

Abstract

Solution processed quantum dot (QD) lasers are one of the holy-grails of nanoscience. They are not yet commercialized because the lasing threshold is too high: one needs < 1 exciton per QD, which is hard to achieve due to fast non-radiative Auger recombination. The threshold can however be reduced by electronic doping of the QDs, which decreases the absorption near the band-edge, such that the stimulated emission (SE) can easily outcompete absorption. Here, we show that by electrochemically doping films of CdSe/CdS/ZnS QDs we achieve quantitative control over the gain threshold. We obtain stable and reversible doping more than two electrons per QD. We quantify the gain threshold and the charge carrier dynamics using ultrafast spectroelectrochemistry and achieve quantitative agreement between experiments and theory, including a vanishingly low gain threshold for doubly doped QDs. Over a range of wavelengths with appreciable gain coefficients, the gain thresholds reach record-low values of ~10^-5 excitons per QD. These results demonstrate an unprecedented level of control over the gain threshold in doped QD solids, paving the way for the creation of cheap, solution-processable low-threshold QD-lasers.

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Jaco J. Geuchies, Baldur Brynjarsson, Gianluca Grimaldi, Indy Du Fossé, Robbert Dijkhuizen, Marijn Koel, Solrun Gudjonsdottir, Ward van der Stam, Wiel H. Evers, Pieter Geiregat, Zeger Hens, and Arjan J. Houtepen "Quantitative electrochemical control over optical gain in colloidal quantum-dot and quantum-well solids", Proc. SPIE 11464, Physical Chemistry of Semiconductor Materials and Interfaces XIX, 114640R (20 August 2020); https://doi.org/10.1117/12.2569413

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