This lecture covers novel concepts in photovoltaic devices, focusing on perovskite materials. It discusses the development of perovskite/silicon and perovskite/perovskite tandem cells, up-scaling techniques, and the investigation of up- and down-conversion processes. The potential of intermediate band gap and selective light emitters is also explored, along with the challenges and advantages of different thin film technologies. The instructor presents the latest advancements in the field, such as the record efficiency of perovskite materials and the stability improvements in up-scaled perovskite cells.