Examination Committee

Prof Henry Hei Ning LAM, CBME/HKUST (Chairperson)
Prof Hoi Sing KWOK, ECE/HKUST (Thesis Supervisor)
Prof Han-Ping D. SHIEH, Department of Photonics & Display Institute, National Chiao Tung University (External Examiner)
Prof Man WONG, ECE/HKUST
Prof Zhiyong FAN, ECE/HKUST
Prof Jiannong WANG, PHYS/HKUST

Abstract

As the efficiency of silicon solar cells is very close to the highest efficiency in theory and the cost-down becomes slowly, there is a pressing need for new technology that promises either significantly higher energy conversion efficiencies or extremely lower processing costs. Metal-halide perovskite is such a promising star since it can be easily processed while exhibiting materials properties approaching GaAs and Si. In this thesis, we will focus on this new emerged photovoltaic technology in terms of its material properties, fabrication process and device structure.

Firstly, we have introduced the fabrication of the perovskite materials with a process called reactive closed space sublimation. We have shown this method has the potential to be large scale, high throughput and low cost. We have achieved the highest efficiency up to 16.2% in small area devices, whereas in large area devices, relatively high efficiency (>14%) have also been demonstrated. Our results indicate the reactive closed space sublimation method is quite suitable for the mass production of the perovskite materials and devices.

Moreover, we have identified that controlling over the perovskite morphology with a bilayer structure is crucial to achieve high efficiency and high reproducibility perovskite solar cells. High efficiency up to 15.2% was achieved even that the perovskite solar cells fabrication was all processed in the ambient condition with high humidity.

Finally, we have explored the magnetron sputtering metal oxides as the charge transport layers for the perovskite solar cells. Particularly, the n-type SnO2 and p-type NiOX have shown their potential in high efficiency perovskite solar cells.