Energy‐Loss Reduction as a Strategy to Improve the Efficiency of Dye‐Sensitized Solar Cells

Abstract

Four weak donor backbones (BT, BTP, BT2, and BT3), featuring stepwise enhanced electron‐donating capacities, are designed and synthesized. The sp 3 type carbons introduced are tethered with auxiliary groups to generate a better electron‐blocking stereoscopic structure. A series of NB dyes are subsequently synthesized from these central cores by end‐capping a strong diphenylamine donor and a planar heterocyclic acceptor 4‐(benzo[c][1,2,5]thiadiazol‐4‐ylethynyl)benzoic acid. The fine‐tuning of steric configurations and energy levels of the resulting dye molecules reduces the energy losses significantly when applied in dye‐sensitized solar cells. These devices offer one of the highest open‐circuit voltages (≈1.03 V) reported so far, and high power conversion efficiencies of 9.6%–12.1% using the NB dyes in combination with a well‐developed cobalt‐tris(4‐methoxyphenyl)amine‐based tandem electrolyte.