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Cavity–Matter Interaction in Weak- and Strong-Coupling Regime: From White OLEDs to Organic Polariton Lasers
Published in Marco Anni, Sandro Lattante, Organic Lasers, 2018
Marco Mazzeo, Fabrizio Mariano, Armando Genco, Claudia Triolo, Salvatore Patanè
Higher current densities of the order of kA/cm2 $ ^{2} $ have been achieved in pulsed OLEDs [40] or in organic light-emitting transistor (OLET) devices [41]. Despite these high current densities, no lasing process has been observed, indicating that electrical losses due to the plasmonic effects or free charge carriers (polarons) take place. In order to reach the lasing threshold, one possibility is to play on the cavity resonator in order to reduce the exciton density needed to trigger stimulated emission. Several resonator architectures can be able to reduce the threshold energy pumping [42], but it is still high and the integration of an electroluminescent device to such optical feedbacks is very difficult.
Emerging photoelectric devices for neuromorphic vision applications: principles, developments, and outlooks
Published in Science and Technology of Advanced Materials, 2023
Yi Zhang, Zhuohui Huang, Jie Jiang
In practical applications, the devices used in artificial vision perception systems generally face the complex device integration problems. Deng et al. [159] selected the organic molecular crystal 5,11-bis(triethylsilylethynyl) anthradithiophene (Dif-TES-ADT) as the photoactive layer to demonstrate a novel organic photo-synaptic device that simultaneously provides photo-sensing and synaptic functions. They constructed an array based on this device to emulate the function of the artificial image perception system. Figure 9(e) shows the EPSC obtained after the array was subjected to light stimulation. The integration of the array is simple, and its emulation of visual recognition and optical image functions is successfully verified. In recent years, organic light-emitting transistors have received much attention as optoelectronic elements for fabricating the new generation of active matrix displays and vision sensors. A long-afterglow [163] organic light-emitting transistor was reported by Chen et al. [164]. It uses the light modulation effect in the IGZO channel layer to power the persistent electroluminescence of the light-emitting material 9,10-bis(4-(9 H-carbazol-9-yl)-2,6-dimethylphenyl)-9,10-diboraanthracene (CzDBA). The array based on this organic light-emitting transistor can be used as a visual UV sensor. It is capable of long-lifetime green light emission in the UV radiation region, demonstrating its great potential as a visual UV microsensor. The human visual system can reduce the noise signal to efficiently select the target information from a large amount of complex information. Hua et al. [71] prepared organic semiconductor transistors using 1,4-bis ((5′-hexyl-2,2’-bithiophen-5-yl) ethyl) benzene (HTEB) monolayer molecular crystals. The light spikes of different numbers, durations and intensities are considered as presynaptic stimuli, while the resulting EPSC is considered as the memory level. This synaptic device has good long-term memory for light spike information, and its generated EPSC can be retained for 109s. In Figure 9(f), an array based on this kind of transistor is implemented to emulate the visual noise reduction function. Different light spike intensities represent signals of different importance. The intensity of light spikes for noisy information is less than that of useful information. The currents of the noise pixels gradually disappeared as the time increased. This result indicates that the information processing process is very similar to that of human vision.