Correlating Photovoltaic Performance of Dye-Sensitized Solar Cell to the Film Thickness of Titania via Numerical Drift-Diffusion Simulations

The thickness of TiO2 film is vital to realize the optimization on photovoltaic performance of dye sensitized solar cells （DSSCs）. Herein, the process of charge separation in DSSCs was simulated by using a drift-diffusion model. This model allows multiple-trapping diffu- sion of photo-generated electrons, as well as the back reaction with the electron acceptors in electrolyte, to be mimicked in both steady and non-steady states. Numerical results on current-voltage characteristics allow power conversion efficiency to be maximized by varying the thickness of TiO2 film. Charge collection efficiency is shown to decrease with film thick- ness, whereas the flux of electron injection benefits from the film thickening. The output of photocurrent is actually impacted by the two factors. Furthermore, recombination rate constant is found to affect the optimized film thickness remarkably. Thicker TiO2 film is suitable to the DSSCs in which back reaction is suppressed sufficiently. On the contrary, the DSSCs with the redox couple showing fast electron interception require thinner film to alleviate the charge loss via recombination. At open circuit, electron density is found to decrease with film thickness, which engenders not only the reduction of photovoltage but also the increase of electron lifetime.

Enzyme-Linked Immunosorbent Assay and Immunochromatographic Strip for Rapid Detection of Atrazine in Three Medicinal Herbal Roots

Objectives:An enzyme-linked immunosorbent assay(ELISA)and colloidal gold-based immunochromatographic(ICG)strip assay will be developed for the rapid and high-throughput detection of atrazine(ATZ)in medicinal herbs.Methods:A monoclonal antibody against ATZ was obtained after the immunization of mice,cell fusion,and hybridoma screening,and the antibody was used to develop direct competitive ELISA(dcELISA)and the ICG strip assay.Results:Both dcELISA and ICG strip methods were established,optimized,and validated for the detection of ATZ in Salviae miltiorrhizae radix et rhizome,Astragali radix,and Isatidis radix.dcELISA had a half-maximum inhibition concentration of 10.56 ng/m L(Salviae miltiorrhizae radix et rhizome),7.6 ng/m L(Astragali radix),and 8.15 ng/m L(Isatidis radix).The limit of detection(LOD)of the ICG strip assay was 12.5 ng/mL(Salviae miltiorrhizae radix et rhizome),12.5 ng/mL(Astragali radix),and 6.25 ng/mL(Isatidis radix)in different herb matrices.Due to the recognition characteristics of the monoclonal antibody for the pesticides ATZ,propazine,sebuthylazine,and prometryn,the detection results of real samples by the two immunoassays were confirmed by liquid chromatography–tandem mass spectrometry,which proved the accuracy and reliability of the established methods.Conclusion:The proposed dcELISA and ICG strip methods were suitable for the rapid,convenient,and high-throughput detection of ATZ in these medicinal herbs.