New P-type Transparent Conducting Oxides
Transparent conducting oxides (TCOs) constitute a unique class of materials combining the seemingly mutually exclusive properties of electrical conductivity and optical transparency in a single material. TCO performance is, thus, crucial to the efficiency of thin film photovoltaics. The ionic character of binary oxides such as ZnO, In2O3 and SnO2 provides excellent n-type conductivity when donor doped, the development of efficient p-type TCOs remains a major challenge. Converting oxides from n-type to p-type via acceptor doping, however, is difficult and these materials exhibit low conductivity due to difficulty in introducing shallow acceptors and large hole effective masses.
This project is a combination of parallel experimental study of fabricating p-type TCOs by Aerosol-Assisted Chemical Vapor Deposition (AACVD) and modelling. The student will use AACVD to make a p-type TCO based on LaCrO3 which shows competitive performance within a structure that can be integrated with other oxide electronic materials. The temperature dependence of the conductivity, hole concentration, transmittance and Seebeck coefficient will be measured. New multi-component oxides of Ti, Zn and Sn, along with doped wider band gap oxides of Mg and Zn, will be explored, as these materials provide the required chemical and structural flexibility.
The configurational space from combining Ti, Sn, Zn, Ga is immense, so high level computational modeling techniques will be employed to find their electronic structures and predict the materials properties controlling TCO performance. This component will enable cogent TCO selection which will be fed back into the continuing material fabrication studies.
The project offers excellent training in materials fabrication and characterisation combined with modelling. Its mix of techniques allows the student to make progress during year 1 when there are breaks due to the modules and there are strong potential collaborations with the other Supersolar hub members.