High quantum yield polymer composite nanomaterial [Eu(µ2-OC2H5)(btfa)(NO3)(phen)]2·phen/PEPC

Abstract

Lanthanide complexes possess a number of unique properties, which make them attractive for practical applications in optoelectronics. Particularly, Eu3+-based complexes display strong emission upon UV or blue-light irradiation owing to the sensitization of lanthanide ions by the coordinating ligands. For various applications in optoelectronics there is a need of materials with high thermo-stability and high emission efficiency. One of possible ways to meet these needs is to incorporate the lanthanide complex into a polymer matrix in order to obtain more stable composite material. In the

present communication we report a luminescent nanocomposite (NC) made of Eu3+-based coordination compound [Eu(µ2-OC2H5)(btfa)(NO3)(phen)]2·phen and an oligomer matrix of poly-N-

epoxypropylcarbazole (PEPC). The nanocomposite shows good PL efficiency along with improved thermal stability.

The nanocomposite [Eu(µ2-OC2H5)(btfa)(NO3)(phen)]2·phen/PEPC was obtained from chemical solutions at different molar ratios of coordination compound into polymer matrix. Deposition of the nanocomposite films on quartz substrates was performed applying the spin-coating method. Photoluminescence (PL) spectra of the NC (Fig. 1) reveal characteristic atomic-like narrow emission

bands associated with internal 4f-4f radiative transitions of Eu3+ ion, 5D0,1→7FJ (J = 0–4). The excitation spectrum (Fig. 2) contains a broad band (≈ 300–500 nm) related to the matrix, as well as a number of narrow excitation bands, determined by the internal transitions within the Eu3+ ion. Variation in the PL emission intensity with Eu3+ complex concentration shows that PL quenching appears at concentration of about 10%, as expected based on literature data. The broad band in the excitation spectrum of the nanocomposite is shifted to infrared, from ~375 to ~402 nm, compared to coordination compound [1]. The intrinsic quantum yield of the NC, evaluated from PL decay profile, is found to be 32.7%. The radiative parameters of the NC are comparable with corresponding values of the original Eu 3+ complex [1] and demonstrates a good potential for practical applications.