A perspective on using experiment and theory to identify design principles in dye-sensitized solar cells

Abstract

Dye-sensitized solar cells (DSCs) have been the subject of wide-ranging studies for many years because of their potential for large-scale manufacturing using roll-to-roll processing allied to their use of earth abundant raw materials. Two main challenges exist for DSC devices to achieve this goal; uplifting device efficiency from the 12 to 14% currently achieved for laboratory-scale ‘hero’ cells and replacement of the widely-used liquid electrolytes which can limit device lifetimes. To increase device efficiency requires optimized dye injection and regeneration, most likely from multiple dyes while replacement of liquid electrolytes requires solid charge transporters (most likely hole transport materials – HTMs). While theoretical and experimental work have both been widely applied to different aspects of DSC research, these approaches are most effective when working in tandem. In this context, this perspective paper considers the key parameters which influence electron transfer processes in DSC devices using one or more dye molecules and how modelling and experimental approaches can work together to optimize electron injection and dye regeneration.

A quantitative model of charge injection by ruthenium chromophores connecting femtosecond to continuous irradiance conditions

“…However, the online version of record will be different from this version once it has been copyedited and typeset. [11][12][13][14][15][16][17] Numerous theoretical and experimental studies [18][19][20][21][22][23][24][25][26][27][28] have attempted to determine the primary steps that govern charge injection efficiency has been attempted, employing well-founded theory to interpret lifetimes extracted from transient absorption (TA) signals with femtosecond [29][30][31][32] to picosecond [33][34][35][36] resolution. In these studies, the observed spectral features were assigned to the relevant chemical species (e.g., oxidized form of the dye, molecular excited state, or the injected electron) and the kinetics of the observed absorption changes with time were typically modelled by using sum-of-exponential (SOE) fits.…”

Novel benzothiazole half-squaraines: model chromophores to study dye–TiO2interactions in dye-sensitized solar cells

“…18 In addition, dye HOMO-LUMO levels are oen calculated using techniques such as density functional theory (DFT) where the energy level data are used to understand electronic spectra, and the HOMO-LUMO locations indicate the potential for electron injection into TiO 2 . 19 .…”

“…8,9,36 Given the strong effect they have on the device performance, these topics are astonishingly rarely studied. 19 In this paper we address the dye-TiO 2 orientation issue through a systematic study using a half-squaraine (HfSQ) dye chromophore where we have incorporated a sulphur atom into the indole moiety as an atomic tag. We have studied this class of dyes previously and found them to be synthetically versatile, reasonably efficient in DSC devices for single (h ¼ 5.0%) 37 or double linker group (h ¼ 5.5%).…”