Researchers from China have found an effective strategy for filling the pinhole defects of organic dye-grafted titania films, enhancing the performance of organic dye-sensitized solar cells employing non-corrosive cobalt redox electrolytes.
Dye-sensitized solar cells (DSCs) use organic dyes to enhance the light-harvesting of inorganic solar cells, altering the wavelengths of incoming light to those better absorbed by the cell in a process known as up- or down-conversion. When dyeing a cell, a good solvent must be used to prevent the dye aggregating, the aim being to create only a monolayer of dye on the surface. However, this creates an incomplete coating of the inorganic surface with the dye, the gaps called ‘pinhole defects,’ which act as sites where the charge-hole pairs created by the absorption of photons recombine easily, significantly reducing current generation and thereby the effectiveness of the cell.
Zhang et al. in the paper Judicious selection of a pinhole defect filler to generally enhance the performance of organic dye-sensitized solar cells detail their quest to solve this problem, creating two bulky model dyes for coating a titania support and three very similar but less bulky ‘fillers.’ The dyes were coated onto the titanium with good solvents and the fillers with poor solvents to maintain the integrity of the dye coating. In every case, the filler reduced open-current voltage, a fundamental measure of efficiency. The net result was an impressive solar-to-electricity energy efficiency of 10.5% under non-concentrated light for their best cell.
The exciting results of this study make it a must-read for those involved with organic solar cells. Additionally, though this is a technical paper specific to dye-sensitized organic solar cells, anyone with interest in solar cells would find interest in this article because the general strategy of defect-filling could be used to reduce interfacial charge recombination in other types of solar cells.
Read the article in EES:
Judicious selection of a pinhole defect filler to generally enhance the performance of organic dye-sensitized solar cells
Min Zhang, Jing Zhang, Ye Fan, Lin Yang, Yinglin Wang, Renzhi Li and Peng Wang
DOI: 10.1039/C3EE42431F, Communication
By Benjamin Britton
