Light emission photoluminescence

Keywords Silicon, germanium, carbon, alloys, nanostructures, optoelectronics, light emission, photoluminescence, electroluminescence, quantum well, quantum wire, quantum dot, superlattices, quantum confinement. 

The solution photoluminescence quantum yields of the copolymers are high (0.4-0.8) and indicate a great potential in light emission applications [60, 64-69],... 

Photoluminescence is a term widely applied to the range of phenomena where light emission occurs from a material after energising by photons. In this section of the book the term is specifically applied to the cases where luminescence occurs after the interaction of luminescent materials with narrow band, higher energy ultraviolet radiation, namely in lighting and plasma display panel applications. 

Copolymers containing alternating l,4-bis(phenylethenyl)benzene, l,4-bis(phenylethenyl)-2,5-dimethoxybenzene or l,5-bis(phenylethenyl)naphthalene chromophores, and dibenzo-24-crown-8 spacers within the polymer backbone, best represented by 87, showed blue light emission in solution, and tunable photoluminescence and electroluminescence depending on the structure of the chromophore. Blends of these copolymers with a small amount of poly(ethylene oxide), and lithium salt as active layers, form efficient light-emitting electrochemical cells <2003JMC800>. 

The thulium (III) ion exhibits spectrally narrow light emission at about 480 nm. Li and coworkers were the first to use the Tm + ion in OLEDs [65]. They prepared a Tm complex Tm(acac)3(phen) and constructed double-layer cells with structure ITO/PVK/Tm complex/Al. The electroluminescence spectrum of the OLED with drive voltage 10 V and the photoluminescence spectrum with excitation wavelength at 350 nm are shown in Figure 11.29. The emitting intensity of 6.0cdm was achieved when a 16 V forward bias voltage was applied. 

The spectral peak locations at 580 nm and 630 nm are identical to what can usually be seen with photoluminescence and regular EL measurements of MEH-PPV. Therefore we conclude that microscopic light emission mechanism in transient... 

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