Theoretical Investigation of Interface Electrostatics of Solid-State Dye-Sensitized Solar cells

Dye-sensitized solar cells (DSSCs) have gathered great attention in recent years due to their low cost, simple fabrication, and high conversion efficiency [1, 2]. The conventional liquid electrolyte based DSSCs suffer low stability, electrode corrosion and electrolyte leakage [3]. Replacing liquid electrolyte with solid-state materials offers stability, easy fabrication and better encapsulation. While replacing the electrolyte with a solid-state material, charge transfer reaction at the interface between mesoporous TiO2 and Spiro-OMeTAD hole transport layer (HTL) becomes a key factor for the solar cell performance [4]. Many processes involved in photoconversion and charge transport especially at the interface remain unexplored. In this work, we present a combined drift-diffusion and density functional (DFT) model to study the interface electrostatics of a solid-state DSSC. We study the role of interface traps, doping, and space charges on the charge transport properties and device efficiency [5]. Using the 3D drift-diffusion, we calculate the electric field, electrostatic potential, charge carrier distribution and current density at the TiO2/HTL interface of the DSSC. We find that interface traps located below the conduction band edge of mesoporous TiO2 influence the accumulation of photogenerated holes and lead a built-in electric field near the interface. Then, using the DFT calculations we investigate the effect of the interface field to the molecular and electronic structure of the organic dye, and the charge injection from the dye in to the transport layers. Ultimately, this study provides a better understanding of the interface energetics, charge injection and its role in the final performance of solid-state DSSCs. Acknowledgements: A. Singh and A. Gagliardi acknowledge funding from TUM International Graduate School of Science and Engineering (IGSSE) and the German Academic Exchange Service (DAAD). E. Radicchib, S. Fantaccic, F. De Angelis acknowledge the Ministero Istruzione dell’Università e della Ricerca (MIUR) and the University of Perugia for the financial support "Dipartimenti di Eccellenza 2018-2022" (grant AMIS) to FDA. [1] U. Bach, et al., Nature 395 (1998) 583. [2] J. Gong, et al., Renewable and Sustainable Energy Reviews 68 (2017) 234–246. [3] G. Boschloo, et al., Accounts of Chemical Research 42 (2009) 1819–1826. [4] B. Mahrov, et al., Applied physics letters 84 (2004) 5455–5457. [5] A. Singh, et al., Journal of Physical Chemeistry C, (Submitted)     «

Dye-sensitized solar cells (DSSCs) have gathered great attention in recent years due to their low cost, simple fabrication, and high conversion efficiency [1, 2]. The conventional liquid electrolyte based DSSCs suffer low stability, electrode corrosion and electrolyte leakage [3]. Replacing liquid electrolyte with solid-state materials offers stability, easy fabrication and better encapsulation. While replacing the electrolyte with a solid-state material, charge transfer reaction at the interfac...     »