CHARACTERIZATION OF CARRIER DECAY MECHANISMS AND QUANTUM YIELD IN COLLOIDAL UPCONVERTING NANOSTRUCTURES
| Author(s) | Lennon, Kyle | |
| Date Accessioned | 2018-09-28T16:33:48Z | |
| Date Available | 2018-09-28T16:33:48Z | |
| Publication Date | 2018-05 | |
| Abstract | With the continued rise to prominence of solar energy, increasing e ort is being focused on developing more e cient solar energy harvesting technologies. Of those technologies, photon upconversion materials have been demonstrated by simulation to o er large potential e ciency boosts. While the systems that can perform photon upconversion are varied, this study focuses on CdSe(Te)/CdS/CdSe nanorod upcon- verting heterostructures. In this study, key aspects of the upconversion mechanism within these structures are examined, and the results are compared between samples with di erent levels of Tellurium doping within the absorber quantum dot to deter- mine the e cacy of Te-doping as a design parameter for heterostructure optimization. For each structure, photoluminescence and upconversion PL measurements are taken to identify the presence of upconverted light. The dependence of the intensity of up- conversion on the incident photon ux is then measured to assess the nature of the upconversion phenomenon. Time-resolved PL measurements are taken to obtain the decay lifetimes associated with carriers that can radiatively recombine. Finally, the e ciency of each structure is probed through upconversion quantum yield (UCQY) measurements in a precisely calibrated integrating sphere. While successful upconver- sion is observed in each structure, power-dependent measurements indicate that the upconversion does not obey the desired purely two-photon mechanism. Moreover, the structures upconvert with low e ciency, producing UCQY values less than 0.001%. However, trends between the structures indicate that adjusting the Te-doping has not had its desired e ect, but has instead caused unintended changes in the structures, such as a pronounced inhomogeneity within the absorber quantum dot. To isolate the e ect of Te-doping and to further optimize the structures, the e ect of this inhomogeneity must be thoroughly examined in future studies. | en_US |
| Advisor | Matthew Doty | |
| Program | chemical engineering | |
| URL | http://udspace.udel.edu/handle/19716/23861 | |
| Publisher | University of Delaware | en_US |
| Keywords | chemical engineering, carrier decay mechanisms, nanostructures | en_US |
| Title | CHARACTERIZATION OF CARRIER DECAY MECHANISMS AND QUANTUM YIELD IN COLLOIDAL UPCONVERTING NANOSTRUCTURES | en_US |
| Type | Thesis | en_US |