Dye-sensitized solar cells (DSSCs) were assembled by using the bougainvillea flowers, red turnip and the purple wild Sicilian prickly pear fruit juice extracts as natural sensitizers of TiO 2 films. The yellow orange indicaxanthin and the red purple betacyanins are the main components in the cocktail of natural dyes obtained from these natural products. The best overall solar energy conversion efficiency of 1.7% was obtained, under AM 1.5 irradiation, with the red turnip extract, that showed a remarkable current density (Jsc = 9.5 mA/cm 2) and a high IPCE value (65% at λ = 470 nm). Also the purple extract of the wild Sicilian prickly pear fruit showed interesting performances, with a Jsc of 9.4 mA/cm 2, corresponding to a solar to electrical power conversion of 1.26%.
References
[1]
Liska, P; Vlachoupoulos, N; Nazeeruddin, MK; Comte, P; Graetzel, M. cis-Diaquabis(2,2′-bipyridyl-4,4′-dicarboxylate)ruthenium(II) sensitizes wide band gap oxide semiconductors very efficiently over a broad spectral range in the visible. J. Am. Chem. Soc？1988, 110, 3686–3687, doi:10.1021/ja00219a068.
[2]
O’Regan, B; Graetzel, M. A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films. Nature？1991, 353, 737–740, doi:10.1038/353737a0.
[3]
Graetzel, M. Solar energy conversion by dye sensitized photovoltaic cells. Inorg. Chem？2005, 44, 6841–6851, doi:10.1021/ic0508371. 16180840
[4]
Yum, JH; Walter, P; Huber, S; Rentsch, D; Geiger, T; Neusch, F; DeAngelis, F; Graetzel, M; Nazeeruddin, MK. Efficient far red sensitization of nanocrystalline TiO2 films by an unsymmetrical squaraine dye. J. Am. Chem. Soc？2007, 129, 10320–10321, doi:10.1021/ja0731470. 17672464
[5]
Campbell, WM; Jolley, KW; Wagner, P; Wagner, K; Walsh, PJ; Gordon, KC; Schmidt-Mende, L; Nazeeruddin, MK; Wang, Q; Graetzel, M; Officer, DL. Highly efficient porphyrin sensitizers for dye-sensitized solar cells. J. Phys. Chem. C？2007, 111, 11760–11762, doi:10.1021/jp0750598.
[6]
Nazeeruddin, MK; Kay, A; Rodicio, I; Humphry-Baker, R; Mueller, E; Liska, P; Vlachopoulos, N; Graetzel, M. Conversion of light to electricity by cis-X2bis(2,2′-bipyridyl-4,4′-dicarboxylate)ruthenium(II) charge-transfer sensitizers (X = Cl-, Br-, I-, CN-, and SCN-) on nanocrystalline titanium dioxide electrodes. J. Am. Chem. Soc？1993, 115, 6382–6390, doi:10.1021/ja00067a063.
Wang, P; Klein, C; Humphry-Baker, R; Zakeeruddin, SH; Graetzel, M. A High Molar extinction coefficient sensitizer for stable dye-sensitized Solar Cells. J. Am. Chem. Soc？2005, 127, 808–809, doi:10.1021/ja0436190. 15656598
[9]
Argazzi, R; Larramona, G; Contado, C; Bignozzi, CA. Preparation and photoelectrochemical characterization of a red sensitive osmium complex containing 4,4′,4′′-tricarboxy-2,2′:6′,2′′-terpyridine and cyanide ligands. J. Photochem. Photobiol. A: Chemistry？2004, 164, 15–21, doi:10.1016/j.jphotochem.2003.12.016.
[10]
Altobello, S; Argazzi, R; Caramori, S; Contado, C; Da Fre, S; Rubino, P; Chone, C; Larramona, G; Bignozzi, CA. Sensitization of nanocrystalline tio2 with black absorbers based on os and ru polypyridine complexes. J. Am. Chem. Soc？2005, 127, 15342–15343, doi:10.1021/ja053438d. 16262377
[11]
Sarto Polo, A; Murakami Iha, NY; Itokazu, MK. Metal complex sensitizers in dye-sensitized solar cells. Coord. Chem. Rev？2004, 248, 1343–1361, doi:10.1016/j.ccr.2004.04.013.
[12]
Fernando, JMRC; Sendeera, GKR. Natural anthocyanins as photosensitizers for dye-sensitized solar devices. Res. Comm. Current. Sci？2008, 95, 663–666.
[13]
Lai, HW; Su, YH; Teoh, LG; Hon, MH. Commercial and natural dyes as photosensitizers for a water-based dye-sensitized solar cell loaded with gold nanoparticles. J. Photochem. Photobiol. A: Chemistry？2008, 195, 307–313, doi:10.1016/j.jphotochem.2007.10.018.
[14]
Tennakone, K; Kumarasinghe, AR; Kumara, GRRA; Wijayantha, KGU; Sirimanne, PM. Nanoporous TiO2 photoanode sensitized with the flower pigment cyanidin. J. Photochem. Photobiol. A: Chem？1997, 108, 193–195, doi:10.1016/S1010-6030(97)00090-7.
[15]
Cherepy, NJ; Smestad, GP; Graetzel, M; Zhang, GJ. Ultrafast electron injection: implications for a photoelectrochemical cell utilizing an anthocyanin dye-sensitized TiO2 nanocrystalline electrode. J. Phys. Chem. B？1997, 101, 9342–9351, doi:10.1021/jp972197w.
[16]
Dai, Q; Rabani, J. Photosensitization of nanocrystalline TiO2 films by anthocyanin dyes. J. Photochem. Photobiol. A: Chemistry？2002, 148, 17–24, doi:10.1016/S1010-6030(02)00073-4.
[17]
Sarto Polo, A; Murakami Iha, NY. Blue sensitizers for solar cells: Natural dyes from Calafate and Jaboticaba. Sol. Energ. Mat. Sol. Cel？2006, 90, 1936–1944, doi:10.1016/j.solmat.2006.02.006.
[18]
Calogero, G; Di Marco, G. Red Sicilian orange and purple eggplant fruits as natural sensitizers for dye-sensitized solar cells. Sol. Energ. Mat. Sol. Cel？2008, 92, 1341–1346, doi:10.1016/j.solmat.2008.05.007.
[19]
Calogero, G; Di Marco, G. Photoelectrochemical solar cell comprising sensitizing anthocyanin and betalain dyes of vegetal or synthetic origin, or mixtures thereof. International patent n°PCT/IT2009/0004682008.
[20]
Gao, FG; Bard, AJ; Kispert, LD. Photocurrent generated on a carotenoid-sensitized TiO2 nanocrystalline mesoporous electrode. J. Photochem. Photobiol. A: Chemistry？2000, 130, 49–56, doi:10.1016/S1010-6030(99)00193-8.
[21]
Zhang, D; Lanier, SM; Downing, JA; Avent, JL; Lum, J; McHale, JL. Betalain pigments for dye-sensitized solar cells. J. Photochem. Photobiol. A: Chem？2008, 195, 72–80, doi:10.1016/j.jphotochem.2007.07.038.
[22]
Tesoriere, L; Allegra, M; Butera, D; Livrea, MA. Absorption, excretion, and distribution of dietary antioxidant betalains in LDLs: potential health effects of betalains in humans. Am. J. Clin. Nutr？2004, 80, 941–945. 15447903
[23]
Nazeeruddin, MK; Zakeeruddin, SM; Humphry-Baker, R; Jirousek, M; Liska, P; Vlachoupoulos, N; Shklover, V; Fischer, C-H; Graetzel, M. Acid–Base equilibria of (2,2‘-Bipyridyl-4,4‘-dicarboxylic acid)ruthenium(II) complexes and the effect of protonation on charge-transfer sensitization of nanocrystalline titania. Inorg. Chem？1999, 38, 6298–6305, doi:10.1021/ic990916a. 11671348
[24]
Castellar, R; Obon, JM; Alacid, M; Fernandez-lopez, JA. Color properties and stability of betacyanins from opuntia fruits. J. Agric. Food Chem？2003, 51, 2772–2776, doi:10.1021/jf021045h. 12696971
[25]
Zabri, H; Gillaizeau, I; Bignozzi, CA; Caramori, S; Charlot, M-F; Cano-Boquera, J; Odobel, F. Synthesis and comprehensive characterizations of new cis-RuL2X2 (X = Cl, CN, and NCS) sensitizers for nanocrystalline tio2 solar cell using bis-phosphonated bipyridine ligands (L). Inorg. Chem？2003, 42, 6655–6666, doi:10.1021/ic034403m. 14552617
[26]
Quin, C; Clark, AE. DFT characterization of the optical and redox properties of natural pigments relevant to dye-sensitized solar cells. Chem. Phys. Lett？2007, 438, 26–30, doi:10.1016/j.cplett.2007.02.063.
[27]
Xagao, AP; Bernard, MC; Hugot-La Goffe, A; Spyellis, N; Loizos, Z; Falaras, P. Surface modification and photosensitisation of TiO2 nanocrystalline films with ascorbic acid. J. Photochem. Photobiol？2000, 132, 115–120, doi:10.1016/S1010-6030(00)00202-1.
[28]
Burke, A; Ito, S; Snaith, H; Bach, U; Kwiatkowski, J; Graetzel, M. The function of a TiO2 compact layer in dye-sensitized solar cells incorporating “planar” organic dyes. Nano Lett？2008, 977–981.
[29]
Pedreno, MA; Escribano, J. Correlation between antiradical activity and stability of betanine from Beta vulgaris L roots under different pH, temperature and light conditions. J. Sci. Food. Agric？2001, 81, 627–631, doi:10.1002/jsfa.851.
[30]
Calogero, G; Di Marco, G; Cazzanti, S; Caramori, S; Argazzi, R; Bignozzi, CA. Natural dye sensitizers for photoelectrochemical cells. Energ. Environ. Sci？2009, 2, 1162–1172, doi:10.1039/b913248c.
