Abstract
We report the synthesis and characterization of the first example of an organic dye, PP1, for p-type dye-sensitized solar cells (DSCs) bearing a phosphonic acid anchoring group. PP1 is structurally related to the benchmarking dye, P1, which possesses a carboxylic acid anchor. The solution absorption spectra of PP1 and P1 are similar (PP1 has λmax = 478 nm and εmax = 62,800 dm3 mol−1 cm−1), as are the solid-state absorption spectra of the dyes adsorbed on FTO/NiO electrodes. p-Type DSCs with NiO as semiconductor and sensitized with P1 or PP1 perform comparably. For PP1, short-circuit current densities (JSC) and open-circuit voltages (VOC) for five DSCs lie between 1.11 and 1.45 mA cm−2, and 119 and 143 mV, respectively, compared to ranges of 1.55–1.80 mA cm−2 and 117–130 mV for P1. Photoconversion efficiencies with PP1 are in the range 0.054–0.069%, compared to 0.065–0.079% for P1. Electrochemical impedance spectroscopy, open-circuit photovoltage decay and intensity-modulated photocurrent spectroscopy have been used to compare DSCs with P1 and PP1 in detail.
Highlights
In n-type dye-sensitized solar cells (DSCs) [1,2,3,4], a wide variety of anchoring domains are used or have been proposed to attach the dye to the semiconductor surface [5], the most common being carboxylic and phosphonic acids
Yields of the Pd-catalysed cross-coupling reaction introducing the phosphonic ester group are rather low and we decided to carry out this transformation as the first step of the multi-step synthesis. (4-Bromophenyl)diphenylamine was treated with HPO(OEt)2 in the presence of Cs2 CO3 with [Pd(PPh3 )4 ] as catalyst under microwave conditions and 1 (Scheme 3) was isolated in 48.8%
We report the first example of an organic dye, PP1, for p-type DSCs bearing a phosphonic acid anchoring group
Summary
In n-type dye-sensitized solar cells (DSCs) [1,2,3,4], a wide variety of anchoring domains are used or have been proposed to attach the dye to the semiconductor surface [5], the most common being carboxylic and phosphonic acids. These anchors may function as carboxylates or phosphonates since the protonation state of the anchoring groups is not usually clearly defined and can have a significant impact of DSC performance [6].
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