Narrowband Spontaneous Emission Amplification from a Conjugated Oligomer Thin Film.

Mohamad S Alsalhi,Mamduh J Aljaafreh,Saradh Prasad

doi:10.3390/polym12010232

Abstract

In this paper, we studied the laser and optical properties of conjugated oligomer (CO) 1,4-bis(9-ethyl-3-carbazo-vinylene)-9,9-dihexyl-fluorene (BECV-DHF) thin films, which were cast onto a quartz substrate using a spin coating technique. BECV-DHF was dissolved in chloroform at different concentrations to produce thin films with various thicknesses. The obtained results from the absorption spectrum revealed one sharp peak at 403 nm and two broads at 375 and 428 nm. The photoluminescence (PL) spectra were recorded for different thin films made from different concentrations of the oligomer solution. The threshold, laser-induced fluorescence (LIF), and amplified spontaneous emission (ASE) properties of the CO BECV-DHF thin films were studied in detail. The ASE spectrum was achieved at approximately 482.5 nm at a suitable concentration and sufficient pump energy. The time-resolved spectroscopy of the BECV-DHF films was demonstrated at different pump energies.

Highlights

Among the several types of organic semiconductor materials, conjugated materials have been subjected to intensive research studies for many years [1,2,3,4,5,6,7,8,9]
We demonstrate the photoluminescence, absorption and mirrorless laser properties of the conjugated oligomer (CO) BECV-DHF thin film under transverse excitation (3rd harmonic Nd: YAG pulsed laser)
The results show that CO BECV-DHF in thin films has a low energy threshold of 0.65 mJ and produces an amplified spontaneous emission (ASE) at 482.5 nm with a full width at half maximum (FWHM) of 6.8 nm

Summary

Introduction

Among the several types of organic semiconductor materials, conjugated materials have been subjected to intensive research studies for many years [1,2,3,4,5,6,7,8,9]. There has been widespread interest in conjugated materials for applications in optoelectronic devices, such as chemical sensors [10], light-emitting diodes [4,7,9], solar cells [5,11,12], and laser optical media [2,6,13,14,15,16,17]. Conjugated materials have appealing photophysical properties for the implementation of optical devices, namely, large stoke shift emission, excellent gain, strong absorption, high-quality factor, and the ability to produce tunable lasers [18,19,20]. The extrapolation of the electrical and optical properties of conjugated polymers throughout the length of the chain is very difficult. Conjugated oligomers (COs) can have similar or better properties by controlling the conjugation length and limiting the number of separations [21,22]

Methods

Results

Conclusion