## 1 Introduction  
In spite of recent developments in new photovoltaic technologies and decreases in the cost of mature ones [1; 2; 3; 4], dye-sensitised solar cells (DSCs) are still of interest to both researchers and industry. This is at least in part due to their application in large-scale built-in photovoltaics (BIPV) as power windows, due to features such as transparency and the range of dye colours which may be employed. Additionaly, DSCs are expected to find significant use in indoor applications in the near future, for which efficiencies over 28% using artificial lighting have already been reported [5], where the DSC absorption spectra was tuned to better match the light source used. DSCs also have a benefit in that they are not significantly affected by partial shading, changes in temperature or the light incident angle, as silicon solar cells tend to be [5; 6; 7; 8]. TiO\({}_{2}\) photoanodes can be fabricated with different degrees of transparency, depending on the particle size and the paste preparation process [9; 10]. Well-dispersed, small particles can result in a high transmission photoanode (>80%) across the visible range [11]. On the other hand, light scattering is a widely employed technique to increase the mean pathlength of photons through the photoanode, leading to an increased likelihood of said photons being absorbed by bound dyes [11; 12; 13]. This is particularly pertinent when the extinction co-efficient of the dye is low, and simply making the photoanode film thicker leads to increased charge recombination. Indeed, many researchers have intentionally tuned the light scattering properties of their particles to enhance the light-harvesting efficiency (LHE) [14; 15; 10; 16]. However, this is less necessary because of recent developments in sensitiser design and is not desirable for most BIPV applications. A large portion of work published on DSC development (-40%, which equates to more than 1200 publications) has been on the synthesis and/or modification of metal oxides, mostly TiO\({}_{2}\), as efficient photoanode materials [17]. The vast majority of synthesised TiO\({}_{2}\) nanoparticles in these reports were dried, calcined and then re-dispersed to make a printable paste [14; 18; 19]. While a handful of exceptions exists where the nanoparticles were kept in suspension after their synthesis [7; 10; 11], producing a transparent film due to the high nanoparticle dispersion. In 2008 [PERSON] et al. reported high-efficiency DSC based on TiO\({}_{2}\) nanoparticles, with solvent transfer from the synthetic medium to the screen-printing paste matrix, where the TiO\({}_{2}\) was sensitised with the ruthenium complex N719. In this case, both small particle (transparent) and a second layer of larger, scattering particles were employed, as well as an anti-reflective film. The optimum thickness of a bi-layer photoanode including a transparent layer and a large scattering layer was 12-14 um, and photovoltaic conversion efficiencies (PCEs) of 9.1% and 10% were reported for the transparent photoanode- and bi-layer (scattering) photoanode-based devices, respectively [10]. A few years later, [PERSON] et al. investigated the effect of photoanode transparency and thickness on DSC performance for BIPV application. Using a protocol without drying their nanoparticles, they were able to obtain a printable paste and then deposit a transparent photoanode, which was subsequently sensitised with N719. Their best PCEs were 5.13% and 6.64% for photoanode thicknesses 8.13 um and 32.2 um, respectively [7]. More recently, [PERSON] et al. provided further insight as they studied the effect of autoclave pressure in hydrothermal synthesis on the pore and particle sizes of non-scattering TiO\({}_{2}\) photoanodes, again sensitised with the N719 dye, with an optimized PCE of 5.63% [20]. Until recently, the organometallic dye N719 has been a staple of DSC research, in spite of high production costs and the low extinction coefficient [21].