This dissertation aims at explorations of two promising renewable energy devices: one is thermoelectric generators (TEGs) and the other is perovskite solar cells (PVSCs). The first half of this dissertation (Chapter 2 & 3) focuses on the simulation study of TEGs while the second half (Chapter 4 & 5) concentrates on the experimental study of PVSCs. Chapter 1 serves as an overall introduction of TEGs and PVSCs. Chapter 2 investigates simulation of segmented TEGs with various state-of-the-art thermoelectric (TE) materials between 300 K and 1000 K. The influence of thermal radiation, electrical and thermal contact effects have been studied. The results show that these effects, if well-regulated, do not prevent segmented TEGs from achieving high efficiency and output power density. In Chapter 3, segmented TEGs have been further modelled to find out the best cost-performance ratios. The results reveal that successful segmentation of TE materials can offer a cost-performance ratio of ~0.86 $ W-1, less than commercially desired cost-effectiveness of 1 $ W-1, while maintaining an efficiency of 17.8% and delivering a power density over 3 Watt cm-2. These results predict the commercial feasibility and competitiveness of segmented TEGs in the same dollar per watt metrics as other renewable energy devices. Chapter 4 presents a rapid layer-specific annealing on perovskite active layer enabled by ultraviolet (UV) light-emitting diode (LED) and efficiency close to 19% is achieved in a simple planar inverted structure. These results justify that if the UV dosage is well-managed, UV light is capable of annealing perovskite into high-quality film rather than simply damaging it. Moreover, the layer-specific photonic treatment allows accurately estimating the deposition energy required to form perovskite film at device quality level. Chapter 5 exhibits an effort towards scalable manufacturing of perovskite solar panels. Perovskite mini-modules have been demonstrated with blade-coating and rapid thermal processing (RTP) in ambient environment. Mini-modules with an active area over 2.7 cm2 exhibit a champion efficiency of 17.73%. These results pave the way for large-scale production of PVSCs through high-speed roll-to-roll printing. Chapter 6 summarizes the conclusions and proposes a possible future work.