Comprehensive control of voltage loss enables 11.7% efficient solid-state dye-sensitized solar cells

Heewon Bahng, Yiming Cao, Ulf Anders Hagfeldt, Ladislav Kavan, Yuhang Liu, Jingshan Luo, Jacques-Edouard Moser, Yasemin Saygili, Yinghui Wu, Chenyi Yi, Shaik Mohammed Zakeeruddin, Weiwei Zhang
2018
Journal paper

Abstract

The relatively large voltage loss (Vloss) in excitonic type solar cells severely limits their power conversion efficiencies (PCEs). Here, we report a comprehensive control of Vloss through efficacious engineering of the sensitizer and redox mediator, making a breakthrough in the PCE of dye-sensitized solar cells (DSSCs). The targeted down-regulation of Vloss is successfully realized by three valid channels: (i) reducing the driving force of electron injection through dye molecular engineering, (ii) decreasing the dye regeneration overpotential through redox mediator engineering, and (iii) suppressing interfacial electron recombination. Significantly, the ‘‘trade-off’’ effect between the dye optical band gap and the open-circuit voltage (VOC) is minimized to a great extent, achieving a distinct enhancement in photovoltaic performance (PCE 4 11.5% with VOC up to 1.1 V) for liquid junction cells. The solidification of the best-performing device leads to a PCE of 11.7%, which is so far the highest efficiency obtained for solid-state DSSCs. Our work inspires further development in highly efficient excitonic solar cells by comprehensive control of Vloss.

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