QDs Sensitizer Design And Regulation Of Energy Transfer In Triplet Energy Transfer System

Triplet-triplet annihilation upconversion（TTA-UC）of organic molecules is a process of converting low-energy photons to high-energy photons,which is widely used in energy and life science fields because of its high photon absorption capacity and high upconversion efficiency.Highly efficient TTA-UC is usually achieved with the help of sensitizers,of which quantum dot sensitizers show a very advantageous upconversion energy gain potential due to their high absorption coefficient,easy and flexible energy regulation and minimal inter-system scampering energy loss and other characteristics.However,quantum dot sensitized TTA-UC still faces bottlenecks:the lack of effective regulation strategies due to insufficient understanding of the mechanism of the core triplet state energy transfer（TET）process in the system,resulting in the low photon upconversion efficiency of the above system;in addition,the commonly used quantum dot sensitizers are mainly composed of group II-VI or III-V elements,represented by Pb S,Cd Se and other materials.Most of these materials contain metal elements with high toxicity,which are polluting to the environment.In this paper,we synthesize green non-toxic Cu In S₂（CIS）quanta as sensitizers to sensitize rhodamine B（Rh B）molecules,and regulate the energy levels and spectra of CIS quantum dots by thermal injection reaction parameters（e.g.,reaction temperature and reaction time）to optimize the construction of an efficient CIS-Rh B triplet-state energy transfer system.The microscopic kinetic evolution of the band-edge bleaching（XB）and rhodamine B triplet state（³Rh B^*）of CIS in the CIS-Rh B complex system was directly observed by transient absorption and time-resolved fluorescence spectroscopy to study the TET process of the system,i.e.,³Rh B^*was gradually generated at almost the same rate as the CIS XB signal gradually decayed within0.01-1μs.Based on the above kinetic process,the triplet-state energy transfer between CIS quantum dots and Rh B molecules is further analyzed.The one-step Dexter electron exchange mechanism of triplet-state energy transfer between CIS quantum dots and Rh B molecules:³CIS^*+¹Rh B→¹CIS+³Rh B^*,thus establishing the triplet-state energy transfer model between them.This study can provide valuable theoretical guidance and reference for the preparation and application of subsequent TTA-UC devices.