Review of Cecile Charbonneau's lecture: Synthesis, Assembly and Processing of TiO2 Nanomaterials and Thin layers in Application to Third Generation Photovotaics

Newport & District Materials Society
,
16 Mar 2016

Synthesis, Assembly and Processing of TiO2 Nanomaterials and Thin Layers in Application to Third Generation Photovoltaics

 

This fascinating lecture was delivered by Dr Cecile Charbonneau who has, in her career to date, moved from Toulouse in France to SPECIFIC in South Wales via the Louvre in Paris and McGill University in Montreal.

Dr Charbonneau first gave an introduction to SPECIFIC which is a research centre based at Swansea University that has a long list of industrial collaborators including global companies such as Tata Steel and BASF. The initials stand for “Sustainable Product Engineering for Innovative Functional Industrial Coatings”. The current major objective is “to use buildings as power stations” with a major area work the development of third generation of photovoltaics. The challenge is to manufacture low cost, high efficiency solar cells that can cover large areas of buildings e.g. the roofs of large industrial sheds.

Central to the design of the new generation of solar cells is a thin layer of TiO2 typically 50-100 nm thick. Different types of cells require a different morphology for this layer if it is function effectively.

For the organic lead halide perovskite type of cell, the TiO2 layer needs to be semi-conducting, compact and pinhole free. The analogy used was to produce a layer that is the thickness of a human hair that gives perfect coverage for the area of a football pitch. The first challenge is the application of the layer using an industrially scalable process. Many options have been considered but current thinking involves a dip or spray followed by a doctor blade arrangement to achieve the required thickness. Initially the coating was produced using TiCl4 as a precursor and then heating in a near infrared oven. This was reasonable effective but it is desirable to reduce the curing temperature both from an energy perspective and to allow a wider range of substrates to be used. Dr Charbonneau has been working on suspending the powder in oxalic acid and then using ultra violet curing at a far lower temperature as an alternative. This work has shown a lot of promise with cell efficiency of 8% achieved in a perovskite cell in the early experiments.

For the alternative solid electrolyte dye sensitized solar cells, the role of the TiO2 layer is different. In this case it needs to be porous and the challenge is to maximise the porosity. The work at SPECIFIC is aimed at achieving the required level of porosity while minimising costs. It has been found that by using a cheaper grade of TiO2 (P25) and mixing it with a small proportion of nano sized TiO2 particles that excellent results can be achieved.

The lecture was followed by a lively question and answer session with the key issues raised by the audience concerning the durability of the coatings and the cost v efficiency equation. Tony Jones proposed a vote of thanks for Dr Charbonneau and wished her and her colleagues well in their research.

There is no doubt that work into harnessing the energy potential of the sun is proceeding apace and that Dr Charbonneau and SPECIFIC are at the forefront of this. The day when the roof of your local TESCO generates enough energy to power the store may not be too far into the future.