1. Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, 999077 Hong Kong
2. Center of Super-Diamond and Advance Films (COSDAF), City University of Hong Kong, Tat Chee Avenue, Kowloon, 999077 Hong Kong
3. Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, 999077 Hong Kong
4. Department of Chemistry and Centre for Processible Electronics, Imperial College London, London W12 0BZ, United Kingdom
5. Hong Kong Institute for Clean Energy, City University of Hong Kong, Tat Chee Avenue, Kowloon, 999077 Hong Kong
6. School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue, Kowloon, 999077 Hong Kong