Sustained biexciton emission in colloidal quantum wells assisted by dopant-host interaction

Spectroscopic Investigation of Structural Perturbations in CsPbCl3 Perovskite Nanocrystals: Temperature- and Excitation-Energy-Dependent Study

“…44 So, the best plausible explanation from the collective scrutinization of PL as well as TA studies is that the thermal energy is inadequate to thermally dissociate the biexciton-driven states and thus makes biexciton transition separable from the excitonic states. 43 Such behavior could only be explained with a model in which the formation rate remains the same irrespective of temperature while the decay rate is dependent upon temperature, which is clearly observed from our transient study (Table S5). 45,46 Further, the decay rate of the biexciton population is quantified in the form of the equation mentioned below 44,45 i k j j j j j y…”

“…Previously, numerous reports have found a concurrent increase in biexciton PL at low temperatures. 43,44 However, the reason for the increase in biexciton PL at low temperatures remains unclear, but our combined analysis of PL and TA gives an analogy of this temperature-dependent process taking place in CsPbCl 3 NCs. So, in order to disentangle this insight, we have compared the biexciton dynamics of CsPbCl 3 NCs as a function of temperature.…”

“…Also, it is an identified fact that the biexciton intensity is inversely proportional to decay rate of the biexciton (γ(T)); thus, at low temperatures PL intensity increases and a negative bleach is observed in the transient data. 43 Effect of Phase Transition on Carrier Temperature and Energy Loss. To further emphasize our results, we have calculated the T c (Figure 4A−C) for CsPbCl 3 NCs for all temperatures under consideration.…”

Mutual Energy Transfer in a Binary Colloidal Quantum Well Complex

“…27−30 Metal ion dopants, which introduce midgap energy levels and radiatively capture the conduction band electrons, can generate a new emission band with a huge Stokes shift. 31,32 An appealing conjecture in the binary complex consisting of doped and undoped CQWs is that if the metal ions can also behave as acceptors, FRET back and forth between doped and undoped CQWs can offer extended capability for FRET-based applications. Herein, encouraged by the new FRET possibility induced by dopants and high FRET efficiency in CQWs, we have explored energy transfer between copper-doped 3 ML CQWs (d-CQWs) and undoped 4 ML CQWs (u-CQWs).…”

“…Both the d-CQWs and u-CQWs are synthesized using modified recipes from our previous work, 27,28,33 and the materials characterization is detailed in our previous work. 27,28,32 The details of the synthesis and material characterization are described in Methods. Two basic requirements for FRET to occur are spatial and energetic overlap.…”