In organic photovoltaics (OPVs), determining the energy-level alignment of a donor and an acceptor is particularly important since the interfacial energy gap between the highest occupied molecular orbital (HOMO) level of a donor and the lowest unoccupied molecular orbital (LUMO) level of an acceptor (E-E) gives the theoretical maximum value of the open-circuit voltage (V). To increase the E-E, non-fullerene acceptors, which have a lower electron affinity (EA) than C, are receiving increasing attention. In this study, we investigated the energy-level alignment at the interface of a boron chloride subphthalocyanine (SubPc) donor and a halogenated SubPc (ClSubPc) acceptor using soft X-ray spectroscopy techniques. The estimated E-E of ClSubPc/SubPc was 1.95 eV, which was significantly higher than that of 1.51 eV found at the interface of C/SubPc. This increased E-E was the origin of the enhanced V in OPVs. Additionally, we studied the molecular orientation of ClSubPc using angle-dependent X-ray absorption spectroscopy. The highly disordered ClSubPc molecules result in low carrier mobility, which contributes to the lower short-circuit current density of the ClSubPc acceptor OPVs than the C acceptor OPVs.

The purpose of this study was to investigate the perception of the school dietitian on superior agricultural products (SAP) and the status of using superior agricultural products in school meals. Questionnaires were distributed to 185 school dietitians after face to face interview, and a total of 181 responses were used for analysis. 82.3% of the respondents were using SAPs in school meals and there was a significant difference between elementary school (95.1%), middle school (76.8%) and high school (66.7%) dietitians (p < 0.001). 85.2% of the dietitians, who were using SAP, were purchasing SAPs through electronic bidding, and the main reason of not using SAPs was the higher price of SAPs than that of general agricultural products. The good agricultural practices (GAP) product was considered the most appropriate agricultural products for school meals by the majority of respondents (66.9%), and organic products was the next (13.3%). In addition, the most important selection criterion for a SAP perceived by school dietitians was safety (58.0%), and the main reason of using SAPs in school meals, when two choices were allowed, was 'to provide healthful food to children' (98.9%). The major barriers to using SAPs in school meals (two choices were allowed) were 'too expensive' (73.5%) and 'unstable supply' (32.6). In conclusion, it was suggested that there should be an improvement in SAP supply and management systems to increase the use of SAPs in school meals. (Korean J Community Nutr 17(3) : 312~320, 2012)

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