Molecular Host−Guest Energy-Transfer System with an Ultralow Amplified Spontaneous Emission Threshold Employing an Ambipolar Semiconducting Host Matrix

Abstract

We report on the characteristics of a host-guest lasing system obtained by coevaporation of an oligo(9,9-diarylfluorene) derivative named T3 with the red-emitter 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran dye (DCM). We demonstrate that the ambipolar semiconductor T3 can be implemented as an active matrix in the realization of a host-guest system in which an efficient energy transfer takes place from the T3 matrix to the lasing DCM molecules. We performed a detailed spectroscopic study on the system by systematically varying the DCM concentration in the T3 matrix. Measurements of steady-state photoluminescence (PL), PL quantum yield (PLQY), time-resolved picosecond PL, and amplified spontaneous emission (ASE) threshold are used to optimize the acceptor concentration at which the ASE from DCM molecules takes place with the lowest threshold. The sample with a DCM relative deposition ratio of 2% shows an ASE threshold as low as 0.6 kW/cm(2) and a net optical gain measured by femtosecond time-resolved pump-and-probe spectroscopy as high as 77 cm(-1). The reference model system Alq(3):DCM sample measured in exactly the same experimental conditions presents an one-order-of-magnitude higher ASE threshold. The ASE threshold of T3:DCM is the lowest reported to date for a molecular host-guest energy-transfer system, which makes the investigated blend an appealing system for use as an active layer in lasing devices. In particular, the ambipolar charge transport properties of the T3 matrix and its field-effect characteristics make the host-guest system presented here an ideal candidate for the realization of electrically pumped organic lasers.

Multicolored Emission and Lasing in DCM-Adamantane Plasma Nanocomposite Optical Films

“…The experimental quantum yields for the studied films were 0.3% for the DCM film and 1.8%, 1.8%, 4.7%, 6.5%, and 10.2% for the DCM-ADA-X films, where X = 1, 2, 4, 5, and 6, respectively. Although these luminescent emissions could be observed by eye under ambient light conditions, the quantum yield values were low but similar to those that have been reported for the direct DCM excitation in sublimated DCM blends with concentrations of ∼10% …”

“…Additional studies are required to optimize the luminescence efficiencies of these nanocomposite films. For example, the use of derivative DCM dye precursors to avoid intermolecular interactions at high concentrations or Förster energy transfer to the DCM from an acceptor dye , are feasible strategies to improve the photoluminescence of the films and reduce the lasing thresholds. However, these results clearly show the available synthetic approaches to control properties such as light absorption, fluorescence, and the refractive index, which are critical to designing optically active thin films by the remote plasma-assisted technique.…”

Hole Hopping Rates in Organic Semiconductors: A Second-Order Cumulant Approach

“…Organic π-conjugated single molecules and polymers have been revealed to be extremely useful building blocks for developing efficient optoelectronic materials. The impressive progresses obtained in the fields of organic light emitting diodes (OLEDs) and solar energy conversion have allowed for the achievement of efficiencies high enough to reach the market, with still high expectations of further improvements. , Organic field-effect transistors (OFETs) are also of great technological interest for the fabrication of low-cost, flexible, and large area logic circuitry. − …”

Low-threshold blue lasing from silk fibroin thin films

“…5 In particular, organic lasers are of great interest due to the ability of molecules and polymers to provide efficient lasing in the solid state. 6,7 Furthermore, the compatibility of organics with natural biomaterials makes organic photonics suitable to develop biocompatible and biodegradable devices. 8 Silk fibroin, the natural protein produced by the Bombyx mori caterpillar, is an attractive material for applications in organic photonics and electronics.…”