Calculation of the Förster Resonance Energy Transfer Parameters in Nanospheres Containing CdSe/ZnS Quantum Dots and Diarylethene

Abstract

An analysis of theoretical model studies of photochromic systems with reversible fluorescence modulation based on polymer nanospheres containing CdSe/ZnS semiconductor quantum dots (QDs), and photochromic diarylethene DAE2 molecules is presented. Based on the known relations of the theory of Förster resonance energy transfer (FRET), a model is constructed for the efficiency of modulation of QD fluorescence E(r) caused by photochromic transformations of DAE2 molecules located near them due to the FRET mechanism. The boundaries of the optimal values of the parameters that affect the efficiency of the fluorescence modulation due to FRET are determined. The efficiency of FRET E(r) is given for some boundary values of the influencing factors. It is shown that E(r) ~ 0.7 can be achieved at distances between donors and acceptors r = 4.5 nm, if one QD with a fluorescence quantum yield Q = 0.4 accounts for at least n = 16 DAE2 molecules (or at Q = 0.8 and n = 8), as well as at distances r = 3 nm (Q = 0.1 and n = 6; Q = 0.4 and n = 2; Q = 0.8 and n = 1). The results obtained can be used to optimize the structure and technology for the synthesis of photochromic luminescent nanospheres.