Although efficiency of Dye Sensitized Solar Cell (DSSC) is still below the performance level of the market dominance silicon solar cells, in the last two decades DSSC has gathered sufficient ...interests because of the simplicity in device fabrication and low material cost, and therefore, DSSC is providing a possibility of solar cells production at a low entry cost. This review presents the research progress made in the implementation of natural pigments in DSSC. These pigments function as dye sensitizers and they play a major role in DSSC by absorbing light, and supplying electrons to the semiconductor matrixes in the cell. The common choices of dyes are the metal complexes, organic and/or natural dyes. A better efficiency with higher durability is observed for DSSC using metal complexes and organic dyes, however, the process of synthesizing these dyes is laborious, costly, and involves the use of toxic materials. As an alternative, natural pigments (dyes) found in plants such as anthocyanin, carotenoid, aurone, chlorophyll, tannin, betalain and many others are accepted as dyes in DSSCs. These natural pigments are easily obtained from fruits, flowers, leaves, seeds, barks and various parts of plants. Despite the limited performance of natural dyes, the prevailing advantages of natural dyes include high absorption coefficients, high light harvesting efficiency, low cost extraction and low toxicity. This review provides insight into the usage of the various natural pigments as sensitizers, the techniques to improve the pigments performance in DSSC, an outlook on the developmental work on the application of natural pigments in DSSC and their limitation. Additionally, the paper discusses the overall operation principle and the recent developments of each component of DSSC, as well as, comparing the material cost between natural dye and synthetic dye DSSC.
•Natural pigments have a promising future as sensitizers in DSSCs.•Anthocyanin, carotenoid, aurone, chlorophyll, tannin and betalain are among the natural pigments used as sensitizers.•Low-cost extraction, vast availability and eco-friendliness are major attractions of natural pigments.•The total fabrication cost for DSSC sensitized with chlorophyll is less than ~€ 2 per Watt peak.
Cyanidin is widely considered as a potential natural sensitizer in dye-sensitized solar cells due to its promising electron-donating and electron-accepting abilities and cheap availability. We ...consider modifications of cyanidin structure in order to obtain broader UV-Vis absorption and hence to achieve better performance in DSSC. The modified molecule consists of cyanidin and the benzothiadiazolylbenzoic acid group, where the benzothiadiazolylbenzoic acid group is attached to the cyanidin molecule by replacing one hydroxyl group. The resulting structure was then computationally simulated by using the Spartan’10 software package. The molecular geometries, electronic structures, absorption spectra, and electron injections of the newly designed organic sensitizer were investigated in this work through density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations using the Gaussian’09W software package. Furthermore, TDDFT computational calculations were performed on cyanadin and benzothiadiazolylbenzoic acid separately, as reference. The computational studies on the new sensitizer have shown a reduced HOMO-LUMO gap; bathochromic and hyperchromic shifts of absorption spectra range up to near-infrared region revealing its enhanced ability to sensitize DSSCs.
Chlorophyll and xanthophyll dyes extracted from a single source of filamentous freshwater green algae (Cladophora sp.) were used to sensitize dye sensitized solar cells and their performances were ...investigated. A more positive interaction is expected as the derived dyes come from a single natural source because they work mutually in nature. Cell sensitized with mixed chlorophyll and xanthophyll showed synergistic activity with improved cell performance of 1.5- to 2-fold higher than that sensitized with any individual dye. The effect of temperature and the stability of these dyes were also investigated. Xanthophyll dye was found to be more stable compared to chlorophyll that is attributed in the ability of xanthophyll to dissipate extra energy via reversible structural changes. Mixing the dyes resulted to an increase in effective electron life time and reduced the process of electron recombination during solar cell operation, hence exhibiting a synergistic effect.
The use of anthocyanin dyes extracted from epidermal leaves of Tradescantia spathacea (Trant) and petals of Ixora coccinea (IX) was evaluated in the application of dye-sensitized solar cells (DSSCs). ...Subsequently, cocktail anthocyanin dyes from these dyes were prepared and how they enhanced the cell’s overall performance was assessed using five different volume-to-volume ratios. Cocktail dyes absorbed a wider range of light in the visible region, thus increasing the cell efficiencies of the cocktail dyes when compared to the DSSC sensitized by individual dyes. The surface charge (zeta-potential), average size of aggregated anthocyanin molecules (zetasizer), and anthocyanin stability in different storage temperatures were analyzed and recorded. Lower size of aggregated dye molecules as revealed from the cocktail dyes ensured better adsorption onto the TiO2 film. Tradescantia/Ixora pigments mixed in 1 : 4 ratio showed the highest cell efficiency of η=0.80%, under the irradiance of 100 mW cm−2, with a short-circuit current density 4.185 mA/cm2, open-circuit voltage of 0.346 V, and fill factor of 0.499. It was found that the desired storage temperature for these cocktail dyes to be stable over time was −20°C, in which the anthocyanin half-life was about approximately 1727 days.
Natural dyes have become a viable alternative to expensive organic sensitizers because of their low cost of production, abundance in supply, and eco-friendliness. We evaluated 35 native plants ...containing anthocyanin pigments as potential sensitizers for DSSCs. Melastoma malabathricum (fruit pulp), Hibiscus rosa-sinensis (flower), and Codiaeum variegatum (leaves) showed the highest absorption peaks. Hence, these were used to determine anthocyanin content and stability based on the impacts of storage temperature. Melastoma malabathricum fruit pulp exhibited the highest anthocyanin content (8.43 mg/L) followed by H. rosa-sinensis and C. variegatum. Significantly greater stability of extracted anthocyanin pigment was shown when all three were stored at 4∘C. The highest half-life periods for anthocyanin in M. malabathricum, H. rosa-sinensis, and C. variegatum were 541, 571, and 353 days at 4∘C. These were rapidly decreased to 111, 220, and 254 days when stored at 25∘C. The photovoltaic efficiency of M. malabathricum was1.16%, while the values for H. rosa-sinensis and C. variegatum were 0.16% and 1.08%, respectively. Hence, M. malabathricum fruit pulp extracts can be further evaluated as an alternative natural sensitizer for DSSCs.
We report results of combined experimental and theoretical studies of black tea waste extract (BTE) as a potential sensitizer for TiO2-dye-sensitized solar cells (DSSCs). UV-vis absorption data ...revealed that BTE contains theaflavin. DSSC sensitized with pigment complexes of BTE showed a photon-energy conversion efficiency of η=0.20%, while a significant increase (η=0.46%) is observed when pH of the pigment solution was lowered. The HOMO and LUMO energy levels were calculated using experimental data of UV-vis absorption and cyclic voltammetry. These calculations revealed a reduction of the band gap by 0.17 eV and more negativity of HOMO level of acidified pigment, compared to that of original pigment. Combined effect of these developments caused the enhanced efficiency of DSSC. Density functional theory (DFT) and time-dependent density functional theory (TDDFT) computational calculations were carried out to study the four theaflavin analogues which are responsible for the dark colour of BTE. According to the calculations, two theaflavin analogues, theaflavin and theaflavin digallate, are the most probable sensitizers in this dye-sensitized solar cell system.
Display omitted
•Layered co-sensitization was evaluated in order to achieve high DSSC performance.•Natural pigments from Ixora and Canarium odontophyllum were extracted.•Adsorption studies were ...carried out for each extracted dyes.•Individual dyes, the mixture and layered co-sensitized were tested in DSSCs.•The layered co-sensitization gave the highest conversion efficiency among all.
This paper describes a double layered co-sensitization in dye sensitized solar cells (DSSCs) by using natural pigments from Ixora flower (Ixora sp. (Rubiaceae)) and the outer dark purple skin of ‘Kembayau’ (Canarium odontophyllum) fruit. UV–vis absorption data revealed that both dyes were anthocyanins. Co-sensitization was done by first adsorbing the dye from C. odontophyllum into TiO2 electrode by dipping, and then by removing adsorbed dye of the top layer of TiO2 using a de-sorption solution before the Ixora sp. dye was allowed to adsorb. Power conversion efficiency of the co-sensitized solar cell was 1.55%. The conversion efficiencies of DSSCs sensitized with Ixora sp. , C. odontophyllum and the mixture of both dyes (1:1) were 0.96%, 0.59% and 1.13% respectively. The superior conversion efficiency achieved by layered co-sensitization is attributed to the high adsorption capacities of Ixora sp. and C. odontophyllum, and the homogeneous monolayer adsorption of Ixora sp. as revealed by Freundlich and Langmuir adsorption isotherms.
Natural dyes from Ixora coccinea (RX) and Bougainvillea sp. (BG) were extracted and these individual dyes as well as the cocktail dye of RX and BG (1:1v/v ratio) were investigated as dye sensitizers ...in dye sensitized solar cells (DSSCs). To analyze the capability of the dyes, various characterization methods were deployed such as incident photon-to-current efficiency (IPCE), current-to-voltage (I-V) characteristics, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It was found that DSSC sensitized with RX performed the best with η=0.76%, followed by the cocktail dye (η=0.40%) and BG (η=0.21%). This best overall performance of RX was attributed to the charge transport resistance (Rtr=3.89Ω), with the highest electron density (ɳs=9.45×1028) and effective diffusion coefficient (Deff=2.43×10−8m2/s), which accounted for high Jsc. Co-dominance performance of DSSC sensitized with cocktail dye was observed where the cocktail dye has demonstrated an improved Voc as compared to RX and improved Jsc against BG, suggesting individual influence from both dyes.
Display omitted
•Dyes were extracted from Ixora and Bougainvillea plants.•DSSCs were sensitized with individual and cocktail dyes.•Performances of the DSSCs were investigated and evaluated.•Co-dominant performance was observed in DSSC using cocktail dye.
•Constituents of COP are found to be potential sensitizers in DSSC.•Results of experimental and DFT/TDDFT calculations are compared.•Anchoring groups of dye molecules are deduced from experimental ...and calculated data.•Multiple anchoring of a dye may affect photo-energy conversion efficiency.
The active constituents of Canarium odontophyllum (COP) were investigated experimentally and theoretically for dye sensitized solar cell (DSSC) application. Three main flavonoid pigments (cyanidin, pelargonidin and maritimein) were detected in COP showing photo-energy conversion efficiencies of 1.43%, 0.87% and 0.60%, respectively. The molecular geometries, electronic structures, optical absorption spectra and proton affinity of these molecules were investigated with DFT/TDDFT. All three molecules displayed π→π* transition dominant in HOMO→LUMO transition. The anchoring groups onto TiO2 surface were deduced from combined experimental and calculated data. All the constituents of COP are potential sensitizers for DSSC.
Display omitted
•Natural dye was extracted from Canarium odontophyllum.•Dye constituents were separated by column chromatography.•DSSCs were sensitized with the constituents.•Improved performances of ...DSSCs using constituents.
Possibility of use of dye extract from skin samples of a seasonal, indigenous fruit from Borneo, namely Canarium odontophyllum, in dye sensitized solar cells (DSSCs) are explored. Three main groups of flavonoid pigments are detected and these pigments exhibit different UV–vis absorption properties, and hence showing different light harvesting capabilities. When applied in DSSCs. The detected pigment constituents of the extract consist of aurone (maritimein), anthocyanidin (pelargonidin) and anthocyanidin (cyanidin derivatives). When tested in DSSC, the highest conversion efficiency of 1.43% is exhibited by cyanidin derivatives, and this is followed by conversion efficiencies of 0.51% and 0.79% for aurone and pelargonidin, respectively. It is shown that individual pigments, like cyanidin derivatives and pelargonidin, exhibit higher power conversion efficiency when compared to that of C.odontophyllum skin pigment mixture (with a conversion efficiency of only 0.68%). The results indicate a possibility of masking effects of the pigments when used as a mixture. The acidification of C.odontophyllum skin pigments with concentrated hydrochloric acid improves the conversion efficiency of the mixture from 0.68% to 0.99%. The discussion in this paper will draw data and observations from the variation in absorption and adsorption properties, the HOMO–LUMO levels, the energy band gaps and the functional group compositions of the detected flavonoids.
PDF
