Four donor-acceptor functionalized molecular materials with symmetrical structures have been synthesized and investigated for their use in optoelectronic applications. These pi-conjugated molecules consist of one electron-donating moiety, for instance, carbazole, triphenylamine, or phenothiazine at the center, and two acceptors at each side. Introduction of different donor moieties decreases the band gaps allowing a fine-tuning of the optical and electrical properties. These materials exhibit multifunctional properties, such as a red light-emitting behavior and a large photovoltaic effect. Red organic light-emitting diodes were fabricated in a facile nondoping configuration based on these materials. Saturated red-emission is observed with a CIE of x = 0.64 and y = 0.33, and an external quantum efficiency of 0.19%. In addition, our first observation of photovoltaic response in the pi-conjugated molecule with donor-acceptor-donor structure is reported. The organic single-component photovoltaic cells were fabricated and characterized. Their open-circuit voltage and short-circuit current density are 1.1 V and 0.07 mA cm(-2), respectively. The photovoltaic effect corresponds to the absorption characteristics of the compound and depends on the nature of the electron-donating group.

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There is an ongoing discussion of the possible effects of nitrogen (N) application on methane (CH 4 ) emission from rice fields. However, the Intergovernmental Panel on Climate Change (IPCC) methodologies for estimating the national inventory of CH 4 emission from paddy rice production do not consider the effects of N addition. To assess the lack of knowledge about N addition effects on inventory estimates, we recently launched a multi-site observation campaign in major rice cultivation regions of China. The observations showed that, across various climate zones, the application of ammonium-based fertilizers at the commonly-adopted levels for fields in China (150 or 250 kg N ha −1 ) generally inhibited accumulative CH 4 emission during rice season (by 28-30% on average) as compared to no N addition. An increase in application from the moderate level of 150 kg N ha −1 to the high rate of 250 kg N ha −1 did not significantly modify CH 4 emission. Our results suggest that disregarding the effect of N fertilization by the IPCC methodologies may not significantly bias CH 4 inventory estimates of China. In regions with much lower N addition levels, however, disregarding the effect of N fertilization may result in the underestimation of Plant Soil (2010) 326:393-401 regional CH 4 emission, since these emissions were mainly derived from studies in regions with relatively high N addition rates.