A series of novel A-D-A structured small molecule photovoltaic (PV) materials [CZ(TDPP) 2 , DPA(TDPP) 2 , PTZ(TDPP) 2 and FL(TDPP) 2 ] with diketopyrrolopyrrole (DPP) as an electron-withdrawing group were synthesized and characterized. These small molecular donors exhibit excellent solubility in common organic solvents. The density functional theory (DFT) calculations demonstrated the intramolecular charge transfer (ICT) behavior of the synthesized PV materials and an efficient charge separation was observed by a fluorescence quenching experiment. In addition, their photophysical and electrochemical properties show that they harvest sunlight over the entire visible spectrum range and keep appropriate energy levels to satisfy the requirement of solution-processable OSCs. Therefore, we explored the PV properties of the synthesized donors by fabricating BHJ solar cells with a typical structure of ITO/PEDOT:PSS/Donors:PC 61 BM/LiF/Al. Among them, CZ(TDPP) 2 revealed a promising performance in PV devices with a power conversion efficiency (PCE) of 1.50%, along with an open-circuit voltage (V OC ) of 0.66 V, a short-circuit current density (J SC ) of 4.12 mA cm À2 , and a fill factor (FF) of 0.44, under an illumination of AM 1.5G (80 mW cm À2 ).
Polychlorinated biphenyls (PCBs) were not widely manufactured or used in China before they became the subject of international bans on production. Recent work has shown they have reached China associated with imported wastes, and that there are considerable unintentional sources of PCBs that have only recently been identified. As such, it was hypothesised that the source inventory and profile of PCBs may be different or unique in China, compared to countries where they were widely used and which have been widely studied. For the first time in this study we therefore undertook a complete analysis of 209 PCB congeners and assessed the contribution of unintentionally-produced PCBs (UP-PCBs) in the atmosphere of China, using polyurethane foam passive air samplers (PUF-PAS) deployed across a wide range of Chinese locations. ∑209 PCBs ranged from 9 to 6856 pg/m 3 (median: 95 pg/m 3 ) during three deployments in 2016-2017. PCB 11 was one of the most detected congeners, contributing 33±19% to ∑209 PCBs. The main sources to airborne PCBs in China were estimated and ranked as pigment/painting (34%), metallurgical industry/combustion (31%), e-waste (23%) and petrochemical/plastic industry (6%). For typical Aroclor-PCBs, e-waste source dominated (>50%). Results from our study indicate that UP-PCBs have become the controlling source in the atmosphere of China and an effective control strategy is urgently needed to mitigate emissions from multiple industrial sources.
Two novel D-π-A-π-D structured small molecules composed of benzothiadiazole and triphenylamine were designed and synthesized. with cyano on the π-bridge exhibited a deep HOMO energy level, resulting in an impressive V(OC) of up to 1.04 V with a PCE of 3.85%, while non-cyano substituted yielded a V(OC) of 0.94 V and a PCE of 1.99%.
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