The synthesis and photophysical study of two novel tert‐butyl modified cyclometalated iridium(III) complexes, i.e., bis(4‐tert‐butyl‐2‐phenylbenzothiozolato‐N,C2′) iridium(III)(acetylacetonate) [(tbt)2Ir(acac)] and bis(4‐tert‐butyl‐1‐phenyl‐1H‐benzimidazolato‐N,C2′) iridium(III)(acetylacetonate) [(tpbi)2Ir(acac)], are reported, their molecular structures were characterized by 13C NMR, 1H NMR, ESI‐MS, FT‐IR, and elementary analysis. Compared with their prototypes without tert‐butyl substituents [(bt)2Ir(acac) and (pbi)2Ir(acac)], (tbt)2Ir(acac) and (tpbi)2Ir(acac) both have shortened phosphorescent lifetimes[(tbt)2Ir(acac) versus (bt)2Ir(acac), 1.1 μs:1.8 μs; (pbi)2Ir(acac) versus (tpbi)2Ir(acac), 0.8 μs:1.82 μs]. Moreover, (tbt)2Ir(acac) has much more improved phototoluminescence quantum efficiencies in CH2Cl2 solution, [(tbt)2Ir(acac), 0.51; (bt)2Ir(acac), 0.26]. Employing them as dopants, high performance double‐layer PLEDs were fabricated. The (tbt)2Ir(acac)‐based and (tpbi)2Ir(acac)‐based PLEDs have the maximum external quantum efficiencies of 8.71 % and 10.25 %, respectively, and high EL quantum efficiencies of 5.92 % and 7.21 % can be achieved under high driven current density of 100 mA cm–2. PLEDs fabricated with both the two phosphors have much broadened EL spectra with FWHM of > 110 nm, which afford the feasibility to be used as dopants in white LEDs, and the best doping concentrations of the two complexes in fabrication of PLEDs were optimized.

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In this paper, we report a Spindt-type field emission array (FEA) with LaB6 as the emitting material. The LaB6 emitters were deposited by e-beam evaporation with low oxide content. As LaB6 in its vapor form is active and absorbs large quantity of residual gases, which oxidizes the LaB6 films, a special e-beam configuration was designed to ensure high evaporation rate which is essential for depositing pure phase LaB6. FEAs with LaB6 emitter tips exhibited an average emission current as high as about 0.23 μA/tip suggesting that LaB6 emitters are promising candidates for high current density vacuum electronic devices.

This paper demonstrates a polycrystalline silicon avalanche mode light-emitting device. The unique N+PN+PN+ cascade structure is designed to enhance light intensity via carrier injection engineering, in which the minority carriers are injected from the forward-biased junction to the light emission junction. Visible light can be observed at the reverse-biased PN junctions when the device operating voltage exceeds 20 V. In particular, the phonon-assisted indirect interband recombination of carriers with excess energy may be the main mechanism of photon emission. A specific junction model is proposed to explain that the light intensity peaks are generated primarily via carrier injection. Comparing the spectral measurements of a single polysilicon N+P junction device and the proposed cascade device shows that the strategy of improving the luminous intensity via carrier injection engineering is feasible and effective.

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