Tuning pentacene based dye-sensitized solar cells. Issue 18 (25th April 2018)

• Record Type: Journal Article
• Authors: Kunzmann, Andreas; Gruber, Marco; Casillas, Rubén; Tykwinski, Rik R.; Costa, Rubén D.; Guldi, Dirk M.
• Is Part Of: Nanoscale. Volume 10:Issue 18(2018)
• Page Start: 8515
• Page End: 8525
• Publication Date: 2018-04-25
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/c8nr01502c
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : Herein, the synthesis, photophysics and electrochemistry of new pentacenes, which are applied in dye-sensitized solar cells, are presented. The electrolyte is optimized using Li + as an additive to enhance electron injection, giving rise to a unique injection event. This leads to a 3-fold increase from previous efficiencies in pentacene-based DSSCs. Abstract : We report on the synthesis, as well as photophysical and electrochemical characterization of a new family of pentacene derivatives, which are applied in n-type dye-sensitized solar cells (DSSCs). As far as the molecular structure of the pentacene is concerned, the synthetic design focuses on cyano acrylic tethered at the 13-position of the pentacene chromophore. The electrolyte composition features increasing amounts of Li + ions as an additive. In general, the increase of Li + concentrations extrinsically reduces the quasi Fermi level of the photoanode and as such facilitates the electron injection process. We demonstrate that pentacene derivatives give rise to a unique charge injection process, which is controlled by the positioning of the quasi Fermi level energies as a function of the Li + concentration. As a result of the enhanced charge injection, device efficiencies as high as 1.5% are achieved, representing a 3-fold increase from previously reported efficiencies in pentacene-based DSSCs. These findings are supported by device analysis in combination with transient absorption and electrochemical impedance spectroscopy assays.