Jeong, Byeong Guk
Ferreira, Tomas A. C.
Chang, Jun Hyuk
Lee, Doh C.
Bae, Wan Ki
Padilha, Lazaro A.
Total Authors: 8
 Univ Estadual Campinas, UNICAMP, Inst Fis Gleb Wataghin, BR-13083859 Sao Paulo - Brazil
 Sungkyunkwan Univ, SKKU Adv Inst Nanotechnol SAINT, Suwon 16419, Gyeonggi Do - South Korea
 Korea Elect Technol Inst, Display Res Ctr, Seongnam Si 13509, Gyeonggi Do - South Korea
 Korea Adv Inst Sci & Technol KAIST, Dept Chem & Biomol Engn, KAIST Inst Nanocentury, Daejeon 34141 - South Korea
Total Affiliations: 4
AUG 19 2020.
Web of Science Citations:
Due to the strong confinement of carriers, electronic interactions play a major role in the performance of colloidal nanocrystals (NCs) as materials for optical gain. Therefore, understanding how to manipulate this phenomenon is essential to achieve feasible devices in the future. In this context, plane colloidal quantum wells (PQWs) have emerged as one of the most promising classes of NCs to be applied as a lasing material, mainly due to the way that carriers and light interact in these structures. Here, a new NC geometry is introduced, called a spherical quantum well (SQW), composed of a CdS/CdSe/CdS (core/well/shell) heterostructure. Similar to PQWs, in this structure it is possible to combine a long biexciton Auger recombination lifetime (>1 ns) with a large absorption cross section and near-unity photoluminescence quantum yield. Also, due to the quantum well structure, this material enables enhanced biexciton interactions even for large volumes. This boosts the gain performance, decreasing the gain threshold to an average number of excitons of (N) T = 0.61 and enhancing the intrinsic gain coefficient. Additionally, by growing thick-shell SQWs it is possible to enhance the absorption cross section, reaching an amplified spontaneous emission (ASE) threshold of 10.6 mu J/cm(2) . Finally, ASE tests demonstrated that this geometry enables enhanced stability, showing no signs of degradation after 287 days of exposure to regular atmospheric conditions and sustained ASE for more than 13 h under femtosecond laser irradiation. These results demonstrate that the SQW structure combines important characteristics of both PQW and core/shell geometries, representing an important step toward a solution-processed quantum dot laser in the future. (AU)