Thin film organic lasers represent a new generation of inexpensive, mechanically flexible devices for spectroscopy, optical communications and sensing. For this purpose, it is desired to develop highly efficient, stable, wavelength-tunable and solution-processable organic laser materials. Here we report that carbon-bridged oligo(p-phenylenevinylene)s serve as optimal materials combining all these properties simultaneously at the level required for applications by demonstrating amplified spontaneous emission and distributed feedback laser devices. A series of six compounds, with the repeating unit from 1 to 6, doped into polystyrene films undergo amplified spontaneous emission from 385 to 585 nm with remarkably low threshold and high net gain coefficients, as well as high photostability. The fabricated lasers show narrow linewidth (<0.13 nm) single mode emission at very low thresholds (0.7 kW cm−2), long operational lifetimes (>105 pump pulses for oligomers with three to six repeating units) and wavelength tunability across the visible spectrum (408–591 nm).

The aim of this work was to improve the laser performance, in terms of threshold and operational lifetime, of lasers based on polymer films doped with perylenediimide (PDI) derivatives as active media. For such purpose, we first investigated the amplified spontaneous emission (ASE) properties of perylene orange (PDI-O), when doped into polystyrene (PS) films. Lower ASE thresholds and larger photostabilities than those of similar films containing another PDI derivative (PDI-C6), recently reported in the literature, have been measured. Results have been interpreted in terms of the photoluminescence efficiency of the films, which depends on the type of 10 molecular arrangement, inferred with the help of nuclear magnetic resonance experiments. We also show that PS films have a better ASE performance, i.e. lower thresholds and larger photostabilities, than those based on poly(methyl methacrylate), which was recently highlighted as one of the best matrixes for PDI-O. Finally, a 1D second-order distributed feedaback laser using PS doped with PDI-O, was fabricated and characterized. This device has shown a threshold significantly lower (by around one order of magnitude) than that of a similar laser based on PDI-C6-doped PS.15

The chemical synthesis of nanographene molecules constitutes the bottom-up approach toward graphene, simultaneously providing rational chemical design, structure-property control and exploitation of their semiconducting and luminescence properties. Here, we report nanographene-based lasers from three zigzag-edged polycyclic aromatics. The devices consist of a passive polymer film hosting the nanographenes and a top-layer polymeric distributed feedback resonator. Both the active material and the laser resonator are processed from solution, key for the purpose of obtaining low-cost devices with mechanical flexibility. The prepared lasers show narrow linewidth ( < 0.13 nm) emission at different spectral regions covering a large segment of the visible spectrum, and up to the vicinity of the near-infrared. They show outstandingly long operational lifetimes (above 10 5 pump pulses) and very low thresholds. These results represent a significant step forward in the field of graphene and broaden its versatility in low-cost devices implying light emission, such as lasers.

as a laser resonator, have found a variety of applications in spectroscopy, [5] optical communications, [6] and sensing. [7][8][9][10] DFB lasers can provide narrow single mode emission (linewidth <1 nm) and require only low pump energy for their operation, i.e., they show a low threshold. The resonator is easily integrated into other devices, and it can be implemented with field-effect-transistor geometry, which promises potential for the development of electrically pumped TFOLs. Moreover, DFB lasers can be mechanically flexible, and their production costs are relatively low. DFB gratings are usually fabricated by electron beam lithography, nanoimprint lithography (NIL), or holographic lithography (HL). [11] A particular advantage of the latter is its capability to produce small structures of different dimensionality over a large area (up to a few cm 2 ) in a simple and low-cost manner, which can be exploited to fabricate wavelength-tunable devices on a single chip.So far, different DFB architectures, with gratings fabricated by various methods, have been reported, [1][2][3][4] whereby efforts have been devoted predominantly to lowering the threshold. The lowest values (<1 kW cm −2 ) have been achieved with lasers whose DFB gratings are engraved on conventional inorganic substrates (e.g., glass or SiO 2 ), onto which the active films are deposited (this configuration will henceforth be denoted as standard; Std). Other studies, aimed at improving device integration, reducing device costs, and achieving mechanical flexibility, have focused either on architectures with gratings imprinted directly on the active film, [12][13][14][15][16][17] or on systems wherein both the active material and the resonator, which is generally located below the active film [18][19][20][21][22] and only in few cases on top of it, [23,24] were processed from solution. Unfortunately, the thresholds of these solution-processed lasers are generally high (>8 kW cm −2 ), except for few exceptions. [19] Finally, several strategies have been proposed in order to accomplish wavelength tunability in a single device. [1][2][3][4] For example, by using multiple gratings (e.g. segmented substrates with a stepped grating period), [25] a wedged-shape active film (i.e. with a continuously variable thickness), [26] mechanical stretching, [27] photoisomerizable azo-polymers, [28] or photochromic molecules doped into the active film. [29] Some works have demonstrated electrical-tuning by combining an elastic DFB laser with an electroactive substrate, [30] or by including a layer contaning a Thin film organic lasers represent attractive light sources for numerous applications. Currently, efforts are devoted to the development of low-cost high-performance and color-tunable devices, whereby both the resonator and the active layer should consist of solution-processable organic materials. Herein, solution-processed distributed-feedback lasers are reported with polymeric resonators on top of active films of perylene orange or carbon-bridged oligo(p-phenylenevi...

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Thin‐film organic lasers are attractive light sources for a variety of applications. Recently, it is reported that carbon‐bridged oligo(p‐phenylenevinylene)s (COPVn with repeating unit n = 1–6) function as unique laser dyes which combine high fluorescence efficiency, wavelength tunability, and both thermal and photostability, making them ideal for use in organic semiconductor lasers. However, in order to obtain such excellent properties, COPVn require blending in a matrix, such as a thermoplastic polymer, thus leading to miscibility issues, limited absorption, and charge transporting properties. Here, high‐performance lasers with a novel active polymer poly‐COPV1, based on the basic unit of COPV1 and prepared as a high‐quality neat film, are reported which overcome the trade‐off between the device performance and durability. The prepared lasers show thresholds 30 times lower and operational lifetimes 300 times longer than devices based on COPV1 dispersed in polystyrene. The low threshold operation allows the poly‐COPV1 lasers to be pumped by a nitride diode laser.

A low-toxicity photopolymer was employed to prepare holographic solar concentrators (HSCs). The main aim of this study is to obtain a versatile holographic element to concentrate the sunlight from different relative positions of the Sun during the day, avoiding the need of expensive tracking systems. Multiplexed holographic elements that combine symmetric and asymmetric holographic lenses of low frequency (545 l/mm) have been recorded in the same plate to concentrate the sunlight from sunrise to sunset. The holographic behavior of HSCs has been studied by measuring the angular diffraction efficiency at 633 nm (close to the maximum response of silicon cells). The efficiency of the complete system “HSC-solar cell” has been evaluated by measuring the short-circuit current (Isc) under solar illumination at different incident angles. This study overcomes the trade-off between good efficiency and high incident acceptance angle, showing an important breakthrough to obtain wide acceptance angle systems.