Lasers based on organic active media have attracted great attention for many years, mainly because they enable wavelength tuning across the visible spectrum. The development of thin film organic lasers brought additional advantages of compactness, mechanical flexibility and low-cost production.[1] Among such devices, distributed feedback (DFB) lasers have demonstrated potential for applications in different areas, such as spectroscopy, optical communications and chemical and biological sensing. For some of these applications, materials operating in the near-infrared (NIR) region, where only a few organic lasers have been demonstrated up to date, are pursued. The principal reason for this lack of NIR emitters is the detrimental effect of fast non-radiative decay following the energy gap law, concentration quenching mechanisms and intra-gap absorption of charge-transfer and triplet states.[2] Hence, a proper understanding of such mechanisms and how to prevent them might lead to a new generation of NIR organic emitters. In this regard, nanographenes (NGs) are emerging materials which offer a great promise for light-emitting devices and integration with other technologies.[3]

In this presentation, the photophysical and laser properties of two series of NGs dispersed in thermoplastic polymer films will be described, both appertaining to the same family of [n,m]peri-acenoacenes in which a number m of [n]acenes are fused into a rhombic nanoflake (see figure). These four-zigzag edged NGs are an excellent platform for investigating the effect of size increase and zigzag edge elongation upon their photophysical and lasing properties.[4,5] Getting insights into such mechanisms provide useful information for the design of materials with emission in the NIR region. In particular, electronic wave function delocalization over the zigzag edge contributes to the red-shift improvement.[6] Following this approach, light amplification in the NIR has been demonstrated with two different NGs of the peri-acenoacene family.

Additionally, the suitability of these compounds for lasing applications has been proved with the manufacture of DFB lasers consisting of active films with top-layer resonators (1D relief gratings fabricated by holographic lithography).[7] The excellent control that provides the lithographic method over the resonator parameters and the quality of the laser architecture enable the manufacture of operational laser devices across the visible spectrum and entering into the NIR region by using the different NGs.