Organic sensitizers with different thiophene units as conjugated bridges:molecular engineering and photovoltaics

Three structural modifications with incorporation of alkyl,alkoxy and vinyl bond into the skeleton of thiophene bridge in D-π-A featured organic sensitizers are specifically developed for insight into their influences on photophysical,electrochemical as well as photovoltaic properties in nanocrystalline TiO_2-based dye sensitized solar cells(DSSCs).The insertion of vinyl bond into the conjugation bridge leads to the molecular planar configuration,and the conjugation bridge of 3,4-ethylenedioxythiophene(EDOT)is prone to positively shift its highest occupied molecular orbital(HOMO).The electrochemical impedance spectroscopy(EIS)results indicate that the grafted long alkyl chain onto thiophene is favorable to suppress dye aggregation when adsorbed onto TiO_2film and modification on interface of TiO_2/dye/electrolyte,resulting in a relatively high open-circuit voltage(V_(oc)).Under optimized conditions,dye LS-4 bearing hexylthiophene as the conjugation bridge shows a relatively high overall conversion efficiency of5.45%,with a photocurrent of 11.61 mA cm^(-2),V_(oc)of 744 mV.

New triphenylamine-based sensitizers bearing double anchoring units for dye-sensitized solar cells

Two organic sensitizers （LI-33 and LI-34） with double anchoring units were synthesized and utilized for dye sensitized solar cells （DSSCs）, which contained thiophene or vinyl thiophene as n-bridge. The introduction of double anchoring units can change their absorption spectra and energy levels in a large degree, thus, the better light-harvesting ability and the convenient electron transfer along the whole molecule can be obtained. The solar cell based on LI-34 exhibited a broad incident photon- to-current conversion efficiency （IPCE） spectrum and high conversion efficiency （η=6.05%） with coadsorbent CDCA.

Donor design and modification strategies of metal-free sensitizers for highly-efficient n-type dye-sensitized solar cells

Dye-sensitized solar cells （DSSCs） cannot be developed without the research on sensitizers. As the key of light harvesting and electron generation, thousands of sensitizers have been designed for the application in DSSC devices. Among them, organic sensitizers have drawn a lot of attention because of the flexible molecular design, easy synthesis and good photovoltaic performance. Recently, new record photovoltaic conversion efficiencies of 11.5% for DSSCs with iodide electrolyte and 14.3% for DSSCs with cobalt electrolyte and co-sensitization have been achieved with organic sensitizers. Here we focus on the donor design and modification of organic sensitizers. Several useful strategies and corresponding typical examples are presented.

The below-ground biomass contributes more to wetland soil carbon pools than the above-ground biomass-a survey based on global wetlands

The biomass of wetland plants is highly responsive to environmental factors and plays a crucial role in the dynamics of the soil organic carbon(SOC)pool.In this study,we collected and analyzed global data on wetland plant biomass from 1980 to 2021.By examining 1134 observations from 182 published papers on wetland ecosystems,we created a comprehensive database of wetland plant above-ground biomass(AGB)and below-ground biomass(BGB).Using this database,we analyzed the biomass characteristics of different climate zones,wetland types and plant species globally.Based on this,we analyzed the differences between the biomass of different plant species and the linkage between AGB and BGB and organic carbon.Our study has revealed that wetland plant AGB is greater in equatorial regions but BGB is highest in polar areas,and lowest in arid and equatorial zones.For plant species,the BGB of the Poales is higher than the AGB but Caryophyllales,Cyperales and Lamiales have higher AGB.Moreover,our findings indicate that BGB plays a more significant role in contributing to the organic carbon pool compared to AGB.Notably,when BGB is less than 1 t C ha^(-1),even slight changes in biomass can have a significant impact on the organic carbon pool.And we observed that the SOC increases by 5.7 t C ha^(-1)when the BGB content is low,indicating that the SOC is more sensitive to changes in biomass under such circumstances.Our study provides a basis for the global response of AGB and BGB of wetland plants to organic carbon.