A molecular photosensitizer achieves a Voc of 1.24 V enabling highly efficient and stable dye-sensitized solar cells with copper(II/I)-based electrolyte
Dan Zhang, Marko Stojanović, Yameng Ren, Yiming Cao, Felix T. Eickemeyer, Etienne Socie, Nick Vlachopoulos, Jacques‐E. Moser, Shaik M. Zakeeruddin, Anders Hagfeldt, Michaël Grätzel
Abstract
Abstract To develop photosensitizers with high open-circuit photovoltage ( V oc ) 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 oc of 1.24 V, with the V oc 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 −2 solar radiation. Remarkably, the co-sensitized solar cell (active area of 2.8 cm 2 ) 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.