Application of hybrid blocking layers in solid-state dye-sensitized solar cells

Philipp Lellig,Jannis W Ochsmann,Peter Müller-Buschbaum,Michael Meister,Jochen S Gutmann,Monika Rawolle,Martin A Niedermeier,Frédéric Laquai

doi:10.1186/s40064-015-1140-2

Abstract

A hybrid blocking layer consisting of a conducting TiO2 network embedded in a ceramic matrix is implemented in a solid-state dye-sensitized solar cell. This novel type of blocking layer is thinner than the classical blocking layer films as shown with SEM and XRR measurements, and thereby the conductivity of the hybrid film is increased by 110%. A percolating TiO2 network, proven by TEM/ESI and GISAXS measurements, allows for the charge transport. Although being thinner, the hybrid film completely separates the rough electrode material from the hole-transport medium in solar cells to avoid the recombination of charge carriers at this interface. In total, the power conversion efficiency of solar cells is improved: the application in photovoltaics shows that the efficiency of devices with the hybrid blocking layer is increased by 6% compared to identical solar cells employing the conventional blocking layer.

Highlights

Hybrid solar cells are cost-effective alternatives to their expensive, silicon-based counterparts (Oregan and Grätzel 1991)
The sol–gel composition with the highest amount of titanium dioxide, resulting in blocking layer films containing 80 wt% TiO2 and 20 wt% of the polymer-derived ceramic material, yields the best results in the application in solar cells, and we focus on this composition
Because the templating polymer diffuses into the pores of the TiO2 network and turns into a ceramic layer in the calcination step, a closed film is obtained which separates the bottom fluorine-doped tin oxide (FTO) electrode from the hole-transport layer: the application in solid-state DCCSs in “Current–voltage characteristics” confirms that the hybrid blocking layer is not penetrated by the hole-transport material (HTM), as the charge recombination is reduced significantly compared to the device omitting the blocking layer

Summary

Introduction

Hybrid solar cells are cost-effective alternatives to their expensive, silicon-based counterparts (Oregan and Grätzel 1991). In dye-sensitized solar cells (DSSCs) inorganic, n-type metal oxides are combined with solid- or liquidstate hole-transport materials (Kwong et al 2004; Wonjoo et al 2008; Gur et al 2006; Andrew et al 2006; Cui et al 2006; Beek et al 1009; Kudo et al 2007). To avoid leakage of the electrolyte and to increase the lifetime of the devices, the liquid electrolyte can be replaced by organic, solid-state hole-transport materials (Snaith and Grätzel 2006; Schmidt-Mende and Grätzel 2006).

Methods

Results

Conclusion