To achieve zero-carbon or zero-energy buildings, buildings must generate energy from on-site renewable energy resources through the concept of building-integrated-photovoltaic (BIPV) systems, and also prevent energy loss to the surroundings through the use of high-performance thermal insulation materials. However, current BIPVs are not suitable for state-of-the-art modern buildings equipped with exterior window glasses on almost all of their surfaces. In this talk, I am going to address the current state of the arts of organic solar cells (OSCs) and perovskite solar cells (PSCs), which are introduced into film-type flexible and semi-transparent BIPV systems. Because organic semiconductors and perovskites are inherently semi-transparent in the visible region and mechanically flexible, in contrast to the opaque, brittle inorganic semiconductors used in conventional BIPVs, they are excellent candidate materials for such window-film-type BIPVs. I will also address the stability issues of both photovoltaics together with a capability to fabricate into large area modules and panels.