Emission dynamics of conjugated oligomer (BECV-DHF)/quantum dot perovskite [formula omitted] composites in solutions

Abstract

In this paper, we performed steady-state spectroscopy and time-resolved optical spectroscopy (TRS) of conjugated oligomer 1,4-bis(9-ethyl-3-carbazo-vinylene)-9,9-dihexyl-fluorene (BECV-DHF)/perovskite quantum dot (PQD) (CsPbBr3) (LUMAR)] composites in solution. Furthermore, we investigated the lasing properties of the composites under nanosecond laser pumping. PQDs were dissolved in various solvents. These solutions were blended to form composite solutions with various weight ratios. The transmission, absorption, fluorescence, and band gap of BECV-DHF and PQDs were measured for various solvents and concentrations. Toluene was found to be the best solvent for blending PQDs and BECV-DHF. The absorption and fluorescence spectra of the blends showed the superposition of features of both materials. TEM analysis showed that the BECV-DHF and PQDs were separated by a distance of 9.75 Å. The calculated Förster radius between the BECV-DHF and PQDs was found to be approximately 50 Å – 60 Å. The presence of PQDs in the BECV-DHF solution reduces the lifetime of the excited states of BECV-DHF, and the fluorescence intensity of the PQDs precedes the fluorescence intensity of the BECV-DHF; hence, the underlying mechanism was Förster-type resonant energy transfer (FRET). The spectrally narrow peaks of PQDs and the BECV-DHF/PQDs were obtained at 523 nm using optical cavity. The spectral narrowing of the full width at half maximum (FWHM) was improved from 15 nm to 8.36 nm compared to BECV-DHF/PQDs with pure PQDs. This strategy of obtaining a short-chain stable laser material via the addition of conjugated oligomer could potentially facilitate the development of efficient optoelectronic devices.