Porphyrin Cosensitization for a Photovoltaic Efficiency of 11.5%: A Record for Non-Ruthenium Solar Cells Based on Iodine Electrolyte

Abstract

Dye-sensitized solar cells (DSSCs) are promising for utilizing solar energy. To achieve high efficiencies, it is vital to synergistically improve the photocurrent (Jsc) and the photovoltage (Voc). In this respect, conjugation framework extension and cosensitization are effective for improving the absorption and the Jsc, which, however, is usually accompanied by undesirably decreased Voc. Herein, based on a rationally optimized porphyrin dye, we develop a targeted coadsorption/cosensitization approach for systematically improving the Voc from 645 to 727, 746, and 760 mV, with synergistical Jsc enhancement from 18.83 to 20.33 mA cm(-2). Thus, the efficiency has been dramatically enhanced to 11.5%, which keeps the record for nonruthenium DSSCs using the I2/I3(-) electrolyte. These results compose an alternative approach for developing highly efficient DSSCs with relatively high Voc using traditional iodine electrolyte.

Characterizations of Efficient Charge Transfer and Photoelectric Performance in the Cosensitization of Solar Cells

“…Apart from CT, a matching of absorption spectra is hoped for full utility of sunlight. Because it is difficult for a single dye to cover the ultraviolet and near-infrared region, cosensitization provides a way with a variety of complementary dyes in order to broaden the absorption spectra range and strength [6][7][8][9][10][11]. A series of porphyrin dyes (XW1-XW4) cosensitized with Dye C1, in which highest cell efficiency has reached 10.45% [11], and the absorption band from dye C1 makes up for poor absorption in 500 nm for porphyrin dye.…”

“…A series of porphyrin dyes (XW1-XW4) cosensitized with Dye C1, in which highest cell efficiency has reached 10.45% [11], and the absorption band from dye C1 makes up for poor absorption in 500 nm for porphyrin dye. Zhu et al used the coabsorption/cosensitization based on a phenothiazine-based electron donor to improve conversion for nonruthenium solar cells (reported to be 11.5%) [6]. PTZ-2 and N719 in phenothiazine-based cosensitization possess efficiency of 8.12% compared with PTZ-2 (5.81%) and N719 (6.97%) [7].…”

Zinc Porphyrins Possessing Three p-Carboxyphenyl Groups: Effect of the Donor Strength of Push-Groups on the Efficiency of Dye Sensitized Solar Cells

“…The primary role of porphyrins in photosynthetic systems have inspired researchers worldwide to develop highly efficient chromophores based on the porphyrin backbone [3][4][5][6][7]. Porphyrins have emerged as the leaders among DSSCs molecules, with exceptional overall conversion efficiencies of 12%-13% under a push-pull framework [8][9][10][11] in competition with ruthenium dyes (11.4%) [12] and organic sensitizers (14.3%) [13][14][15][16]. Though efficient, their disadvantages like multistep syntheses, low overall yields and poor stability may hamper their practical applications.…”

Molecular Engineering Combined with Cosensitization Leads to Record Photovoltaic Efficiency for Non‐ruthenium Solar Cells

“…[7][8][9][10] Based on ap orphyrin derivative containing facially encumbering alkoxy groups to suppress dye aggregation, [7] Xie et al initially developed the porphyrin dye XW1 (Figure 1) by employing ac arbazole group as an electron donor and a4 -ethynyl benzoic acid moiety as the electron acceptor.…”

“…[10] In XW9,t he phenothiazine is directly attached to the meso position, which leads to aphotovoltaic efficiencyof 8.2 %i nD SSC.T he introduction of an ethynylene bridge between the phenothiazine and the porphyrin framework in XW10 enhances light absorption in the near-IR region, and thus an improved efficiency of 8.6 %w as achieved. A benzothiadiazole (BTD) group was inserted into XW11 as an additional electron acceptor to strongly red-shift the onset wavelength to 830 nm, giving ah igh J sc of 18.83 mA cm À2 , although efficiencyd ecreased to 7.8 %o wing to ad ecreased V oc of 645 mV caused by dye aggregation.…”