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Controlling dye coverage instead of addition of organic acid to reduce dye aggregation in dye-sensitized solar cells
摘要： The photo-generated electron injection yield of dye-sensitized solar cells (DSSCs) based on donor-acceptor conjugated dyes is lowered by the aggregation of surface adsorbed organic dyes that pose a low-photoenergy conversion efficiency. Coadsorbates used to prevent the aggregation cause to decompose or detach the dye molecules anchored on the TiO2 surface. In this study, the effect of coadsorption of organic acid and organic dyes on photovoltaic performances was systematically scrutinized by means of adsorption isotherms and photovoltaic measurements. Our laboratory synthesized {0 1 0}-faceted TiO2 (PA TiO2) and P25 TiO2 were used as meso-porous nanocrystals, D149 organic dye was used as a sensitizer and cheno-deoxycholic acid, CDA, was used as a coadsorbate. The coadsorption of CDA reduces the adsorption parameters, maximum adsorption density (Qm) and adsorption constant (Kad), and the reduction depended on the type of TiO2. The photovoltaic performance indicates that the D149 dye has the best dye coverage at around 70% for the effective photovoltaic energy conversion. The coadsorption of CDA increased the photovoltaic performances of DSSCs based on P25 TiO2 but, CDA decreased the photovoltaic performances of DSSCs based on PA TiO2 due to the reduction of the dye coverage below 70%. The results suggest that the coadsorption of organic acids is not necessary if the particular TiO2 can maintain its coverage at the best coverage. Thus, the requirement of coadsorbates to reduce the dye aggregation depends on the type of TiO2 used in DSSCs.
关键词： Coverage,Adsorption isotherms,Coadsoptions,Aggregations,Photovoltaic performances,Dye-sensitized solar cells
更新于2025-09-23 15:21:01
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Rational Design of Phenothiazine-Based Organic Dyes for Dye-Sensitized Solar Cells: The Influence of ??-Spacers and Intermolecular Aggregation on Their Photovoltaic Performances
摘要： Power conversion efficiency (PCE) is one of the important factors in influencing the overall performance of dye-sensitized solar cells (DSSCs), and precise prediction of PCE is a feasible strategy for preparing highly-efficient DSSCs devices. In this work, we designed a series of phenothiazine-based organic dyes by introducing different π-spacers including the 4-isopropyl-4H-dithieno[3,2-b:2′,3′-d]pyrrole (DTP) and 2,7-dihydronaphtho[1,2-d:5,6-d']diimidazole (NDI) to tune their photovoltaic properties. The present studies reveal that the PCE value of the DTP-based dye is estimated to 8.55%, in excellent agreement with the experimentally available value (8.19%) observed in the reported analogue. In comparison to DTP, the strong electron-deficiency NDI group induces a remarkable red-shifting of maximum absorption band, broadening the optical absorption into the near-infrared region. As a consequence, the NDI-based dye achieves an impressive PCE value of 15.51%, which is expected to be a potential organic dye applied in DSSCs.
关键词： Intermolecular aggregation,Phenothiazine-based organic dyes,π-spacers,Photovoltaic performances,Dye-sensitized solar cells
更新于2025-09-19 17:13:59
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The sensitization effect of anthocyanin and chlorophyll dyes on optical and photovoltaic properties of zinc oxide based dye-sensitized solar cells
摘要： In this work, natural dyes based on anthocyanin and chlorophyll pigments were extracted from the powder of P. rubra flowers and S. androgynous leave respectively and used as sensitizers to fabricate zinc oxide (ZnO) based dye-sensitized solar cell (DSSC). It was observed in optical properties analysis that anthocyanin molecules formed a better bond with ZnO surface compared to chlorophyll. Moreover, anthocyanin sensitized ZnO also exhibits higher increment in nanoparticles diameter compared to that of chlorophyll sensitized ZnO due to the chemical absorption occurant. The anthocyanin sensitized DSSC also shows better photovoltaic performance with power conversion efficiency (PCE) of 0.038% compared to chlorophyll sensitized DSSC which exhibited PCE value of 0.014% due to better charges transfer at the interface between the dye molecule and ZnO nanoparticle.
关键词： photovoltaic performances,optical properties,chlorophyll,anthocyanin
更新于2025-09-16 10:30:52
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Designing a thiophene-fused quinoxaline unit to build D–A copolymers for non-fullerene organic solar cells
摘要： In this work, a kind of thiophene-fused quinoxaline (QXT) unit has been designed and synthesized as an electron-deficient unit to build two D-A conjugated copolymers (PBDTT-QXT-TF1 and PBDTT-QXT-TF2) with a thiophene ring as "π-bridge" and thienyl substituted benzo[1,2-b:4,5-b’]dithiophene (BDTT) unit as an electron-rich unit, in which two adjacent side-chain thiophene rings with different number of fluorine atoms have been introduced at 2,3-position of QXT unit. It is found that the fusion of a thiophene ring onto QX unit can result in a red-shift of absorption and narrow the optical bandgap through stabilizing the quinoid structure of the conjugated backbone, and the introduction of carboxyl group at the fused thiophene can reduce the HOMO energy level that is favorable for the enhancement of VOC of the organic solar cells (OSCs). However, the introduction of fused thiophene ring results in partially twist of conjugated backbone, thus attenuating the intramolecular charge transfer (ICT) absorption intensity and finally lead to the decrement of the JSC for the OSCs. Therefore, the corresponding OSC devices based on the PBDTT-QXT-TF1 or PBDTT-QXT-TF2 with IDIC acceptor show much high VOC but low JSC. In addition, the introduction of side-chain thiophene rings with different number fluorine atoms also regulates the energy levels and the structural crystallinity, thus further influencing the photovoltaic performances. By comparison, the PBDTT-QXT-TF1:IDIC blended film exhibits higher and more balanced hole/electron charge mobilities than the PBDTT-QXT-TF2:IDIC blended film, and PBDTT-QXT-TF1:IDIC based device shows higher power conversion efficiency (PCE) of 6.67 % (VOC = 0.951V, JSC =11.56 mA cm?2 and FF = 60.65 %) than PBDTT-QXT-TF2:IDIC based device with a PCE of 5.12 % (VOC = 0.975V, JSC = 9.78 mA cm?2 and FF = 53.61 %).
关键词： Thiophene-fused quinoxaline,Organic solar cells,Photovoltaic performances,D-A copolymer
更新于2025-09-12 10:27:22