There is a pressing need to accelerate the development of advanced energy technologies in order to address the global challenges of clean energy, climate change and sustainable development [1]. Solar energy is the cleanest, most abundant renewable energy source available, and plays a key role in the development of sustainable energy systems. The solar power generation capability in the United States (U.S.) has gone through an exponential growth in the past decade. The U.S. has installed 1,393 megawatts (MW) of solar photovoltaics (PV) in the second quarter of 2015 to reach 22.7 gigawatts (GW) of total installed capacity. This is enough to power 4.6 million American homes [2]. Globally, by the end of 2015, the PV installation capability reached 233 GW.