Chen H.-A.Lee M.-H.Chen C.-W.CHUN-WEI CHEN2019-11-272019-11-27201620507534https://www.scopus.com/inward/record.uri?eid=2-s2.0-84974574162&doi=10.1039%2fc6tc00773b&partnerID=40&md5=47014cd508ef9f703b887d5ff7183b8chttps://scholars.lib.ntu.edu.tw/handle/123456789/432797The recently emerging class of solid-state hybrid organic-inorganic perovskite-based solar cells has demonstrated remarkably high power conversion efficiencies of up to ∼20%. It is expected that a detailed understanding of wavelength-(or energy-)dependent optical transition processes for light harvesting of perovskite solar cell materials will be a crucial factor to further improve the photovoltaic performances. In this work, we would like to employ the first-principles calculations to investigate the wavelength-(or energy-)dependent optical transition mechanism for light harvesting of the CH3NH3PbI3 perovskite material. A method called the band-resolved optical constant analysis technique was developed to investigate the wavelength-(or energy-)dependent optical absorption mechanism of the perovskite material. Based on the analyses, we are able to visualize and quantize the detailed wavelength-(or energy-)dependent optical transition processes involved in the broad absorption spectrum of a perovskite material, which provides deep insight into the understanding of the light-harvesting mechanism of this promising photovoltaic material. © The Royal Society of Chemistry.[SDGs]SDG7Absorption spectroscopy; Calculations; Electromagnetic wave absorption; Light absorption; Optical transitions; Perovskite; Perovskite solar cells; Solar power generation; Absorption mechanisms; Analysis techniques; First-principles calculation; High power conversion; Hybrid organic-inorganic; Photovoltaic materials; Photovoltaic performance; Transition mechanism; Solar cellsjournal article10.1039/c6tc00773b2-s2.0-84974574162