Naphthalene diimide-based cathode interlayer material enables 20.2%efficiency in organic photovoltaic cells

Cathode interlayer(CIL)materials play an important role in improving the power conversion efficiency(PCE)of organic photovoltaic(OPV)cells.However,the current understanding of the structure-property relationship in CIL materials is limited,and systematic studies in this regard are scarce.Here,two new CIL materials,NDI-PhC4 and NDI-Ph C6 were synthesized by varying the alkylamine chain length on the NDI-Ph core.Our investigation reveals a systematic variation in the physical and chemical properties of these materials with increasing alkylamine chain length.Specifically,we observe a sequential decrease in melting point and self-doping effect,accompanied by an enhancement in crystallinity.Among these CIL materials,NDI-PhC4 has a notable balance across various performance metrics.It also exhibits excellent surface modification capabilities,leading to a low surface roughness.Consequently,OPV cells based on NDI-PhC4 achieve a PCE of 20.2%,which is one of the highest reported efficiencies for OPV cells.In addition,the appropriate melting point of NDI-PhC4 contributes to the excellent stability of OPV cells.

1.4-nm Intergrade Mineral in Soils of Snbtropical China:A Review

This paper is a review of some advances in the studies on 1.4-nm intergrade mineral of soils in sub-tropical China. 1) 1.4-nm intergrade mineral occurs ubiquitously in soils of subtropical China. The 1.4-nmrnineral in red soil and yellow soil is mainly 1.4-nm intergrade mineral, and in acidic yellow-brown soil (pH< 5.5) is verniiculite alone or 1.4-nm intergrade mineral together with vermiculite. The distribution and thecontent of 1 .4-nm intergrade mineral in the mountain soils are more widespread and higher than those of thecorresponding soils in horizontal zone. 2) The interlayer material of 1.4-nin intergrade mineral ui these soilsappears to be hydroxy-Al polymers instead of hydroxy-Fe, proto-imogolite or kaolin-like material. There isa significant positive correlation between Al amount extracted from the soil with sodium citrate after DCBextraction and pH value of the citrate solution after the extraction. The citrate can also extract a certainamount of silicon from the soil, but the silicon may not come from interlayer of 1.4-nm intergrade mineral.3) It was seldom studied that either vermiculite or smectite did the natural 1.4-nm intergrade mineral comefrom in soil, or it was commonly thought to come from vermiculite. A recent report has revealed that itcan come from smectite. There are some different behaviors between the 1.4-nm intergrade mineral derivedfrom vermiculite and that from smectite. For example, they exert different influences on the formation ofgibbsite. The 1.4-nm intergrade mineral derived from smectite may promote the formation of gibbsite in theyellow soil. 4) The type of 1.4-nm minerals in soils. i.e., vermiculite or 1.4-nm intergrade mineral, may besignificant to soil properties, such as soil acidity, exchangeable Al, electric charge aiiiount and specific surfacearea. Therefore, the management for the soil in which 1.4-nm mineral is mainly 1.4-nm intergrade mineralor vermiculite should be dealt with differently.