Laser processing of TiO2 films for dye solar cells

We have analysed and optimised a laser process for the sintering of the TiO2 layers in dye solar cells (DSCs). Through a thermographic characterisation of the process, we show that it is possible to scale and process large areas uniformly (16 cm2). We fabricated DSCs with nanocrystalline (nc)-TiO2 films sintered by using pulsed ultraviolet laser with an average output power P varying from 1 W to 7 W whilst mainting a constant power conversion efficiency eta. The highest efficiency reached for a laser sintered DSC was 7%. The time required to sinter 1 m2 of nc-TiO2 film was found to decrease hyperbolically with P, which is important for determining process takt times. We quantified the embodied energy (EE) required to sinter 1 m2 of the active TiO2 layer for a variety of different processes, and found that the EE for the laser sintering process with a system wall plug efficiency of 3.5% to be competitive with the more conventional oven and belt furnace treatments. We outline the main features required from a laser system to carry out an efficient, energetically favourable and industrially applicable automated process with competitive throughput.