A molecular photosensitizer achieves a V<sub>oc</sub> of 1.24 V enabling highly efficient and stable dye-sensitized solar cells with copper(II/I)-based electrolyte.

Zhang, Dan; Stojanovic, Marko; Ren, Yameng; Cao, Yiming; Eickemeyer, Felix T; Socie, Etienne; Vlachopoulos, Nick; Moser, Jacques-E et al. · Nat Commun · 2021

basic_science · Level V

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Abstract

To develop photosensitizers with high open-circuit photovoltage (V<sub>oc</sub>) is a crucial strategy to enhance the power conversion efficiency (PCE) of co-sensitized solar cells. Here, we show a judiciously tailored organic photosensitizer, coded MS5, featuring the bulky donor N-(2',4'-bis(dodecyloxy)-[1,1'-biphenyl]-4-yl)-2',4'-bis(dodecyloxy)-N-phenyl-[1,1'-biphenyl]-4-amine and the electron acceptor 4-(benzo[c][1,2,5]thiadiazol-4-yl)benzoic acid. Employing MS5 with a copper (II/I) electrolyte enables a dye-sensitized solar cell (DSC) to achieve a strikingly high V<sub>oc</sub> of 1.24 V, with the V<sub>oc</sub> deficit as low as 130 mV and an ideality factor of merely 1.08. The co-sensitization of MS5 with the wider spectral-response dye XY1b produces a highly efficient and stable DSC with the PCE of 13.5% under standard AM1.5 G, 100 mW cm<sup>-2</sup> solar radiation. Remarkably, the co-sensitized solar cell (active area of 2.8 cm<sup>2</sup>) presents a record PCE of 34.5% under ambient light, rendering it very attractive as an ambient light harvesting energy source for low power electronics.