Print Email Facebook Twitter Quantitative Electrochemical Control over Optical Gain in Quantum-Dot Solids Title Quantitative Electrochemical Control over Optical Gain in Quantum-Dot Solids Author Geuchies, J.J. (TU Delft ChemE/Opto-electronic Materials) Brynjarsson, Baldur (Student TU Delft) Grimaldi, G. (TU Delft ChemE/Opto-electronic Materials) Gudjónsdóttir, S. (TU Delft ChemE/Opto-electronic Materials) van der Stam, W. (TU Delft ChemE/Opto-electronic Materials) Evers, W.H. (TU Delft BN/Technici en Analisten) Houtepen, A.J. (TU Delft ChemE/Opto-electronic Materials) Date 2020 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 difficult to achieve because of fast nonradiative 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 of 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 ∼1 × 10-5 excitons per QD. These results demonstrate a high level of control over the gain threshold in doped QD solids, opening a new route for the creation of cheap, solution-processable, low-threshold QD lasers. Subject dopingelectrochemistryoptical gainquantum-dotstransient absorption spectroscopyultrafast spectroelectrochemistry To reference this document use: http://resolver.tudelft.nl/uuid:6b04c4d4-1117-4818-8802-c84b04cc287d DOI https://doi.org/10.1021/acsnano.0c07365 ISSN 1936-0851 Source ACS Nano (online), 15 (1), 377-386 Part of collection Institutional Repository Document type journal article Rights © 2020 J.J. Geuchies, Baldur Brynjarsson, G. Grimaldi, S. Gudjónsdóttir, W. van der Stam, W.H. Evers, A.J. Houtepen Files PDF acsnano.0c07365.pdf 5.24 MB Close viewer /islandora/object/uuid:6b04c4d4-1117-4818-8802-c84b04cc287d/datastream/OBJ/view