Katherine Hooper

Near Infrared Radiation as a Rapid Heating Technique for TiO2Films on Glass Mounted Dye-Sensitized Solar Cells

Near infrared radiation (NIR) has been used to enable the sintering of TiO2 films on fluorine-doped tin oxide (FTO) glass in 12.5 s. The 9 µm thick TiO2 films were constructed into working electrodes for dye-sensitized solar cells (DSCs) achieving similar photovoltaic performance to TiO2 films prepared by heating for 30 min in a convection oven. The ability of the FTO glass to heat upon 12.5 s exposure of NIR radiation was measured using an IR camera and demonstrated a peak temperature of 680°C; glass without the 600 nm FTO layer reached 350°C under identical conditions. In a typical DSC heating step, a TiO2 based paste is heated until the polymeric binder is removed leaving a mesoporous film. The weight loss associated with this step, as measured using thermogravimetric analysis, has been used to assess the efficacy of the FTO glass to heat sufficiently. Heat induced interparticle connectivity in the TiO2 film has also been assessed using optoelectronic transient measurements that can identify electron lifetime through the TiO2 film. An NIR treated device produced in 12.5 seconds shows comparable binder removal, electron lifetime, and efficiency to a device manufactured over 30 minutes in a conventional oven.

High throughput fabrication of mesoporous carbon perovskite solar cells

The screen printed mesoporous carbon perovskite solar cell has great potential for commercialisation due to its scalable deposition processes and use of inexpensive materials. However, each layer requires long high temperature heating steps to achieve the necessary sintering and porosity, which is very time and energy intensive for large scale production. Near infrared processing is demonstrated here to reduce the heating time of mesoporous layers within a fully printed lead halide perovskite solar cell from 2 hours to 30 seconds. A stabilised efficiency of 11% was achieved by processing in 30 seconds, identical to that of devices heated in 2 hours. For the first time the effect of residual binder in the carbon electrode on the electron lifetime and charge transfer within devices has been investigated. Furthermore cross section EDX mapping of perovskite infiltration provides a greater understanding into the processing requirements of these devices vital to enable commercialisation.

Spray PEDOT:PSS coated perovskite with a transparent conducting electrode for low cost scalable photovoltaic devices

Organic–inorganic lead halide perovskite materials are an attractive candidate for low-cost thin-film photovoltaics but in order to successfully rival other technologies, it is critical to focus research on addressing the potential bottlenecks to commercialisation. The conventional hole transporter spiro-OMeTAD and evaporated gold contact are unsuitable for commercialisation due to the cost. This study introduces a method for fabricating perovskite devices without spiro-OMeTAD. Instead, PEDOT:PSS was applied directly to the perovskite material using a carefully controlled spray process. The water hyphen containing PEDOT:PSS used was spray coated onto the perovskite film with careful drying to provide a 55-nm-thick interlayer between the perovskite and the electrode providing hole collection. XRD analysis showed that by controlled application, it was possible to avoid water-induced perovskite degradation. The device was completed using a previously demonstrated transparent conducting adhesive electrode based on vertically orientated channels of PEDOT:PSS within an acrylic adhesive instead of evaporated gold. Fully fabricated devices gave comparable performance to those without spiro-OMeTAD.