Chen, H.-W.H.-W.ChenSakai, N.N.SakaiJena, A.K.A.K.JenaSanehira, Y.Y.SanehiraIkegami, M.M.IkegamiHo, K.-C.K.-C.HoMiyasaka, T.T.MiyasakaKUO-CHUAN HO2018-09-102018-09-102015http://www.scopus.com/inward/record.url?eid=2-s2.0-84928994621&partnerID=MN8TOARShttp://scholars.lib.ntu.edu.tw/handle/123456789/391300Amplified photocurrent gain has been obtained by photodiodes of inorganic semiconductors such as GaAs and Si. The avalanche photodiode, developed for high-sensitivity photodetectors, requires an expensive vapor-phase epitaxy manufacture process and high driving voltage (50-150 V). Here, we show that a low-cost solution-processed device using a planar-structured ferroelectric organo-lead triiodide perovskite enables light detection in a large dynamic range of incident power (10-7-10-1 W cm-2) by switching with small voltage (-0.9 to +0.5 V). The device achieves significantly high external quantum conversion efficiency (EQE) up to 2.4 × 105% (gain value of 2400) under weak monochromatic light. On a single dual-functional device, incident small power (0.2-100 μW cm-2) and medium to large power (>0.1 mW cm-2) are captured by reverse bias and forward bias modes, respectively, with linear responsivity of current. For weak light detection, the device works with a high responsivity value up to 620 A W-1. © 2015 American Chemical Society.amplification; ferroelectricity; perovskite photovoltaic cell; photoconductivity; photodetector[SDGs]SDG7Amplification; Chemical detection; Ferroelectricity; Perovskite; Photoconductivity; Photodetectors; Photodiodes; Photoelectrochemical cells; Photons; Photovoltaic cells; Functional devices; Inorganic semiconductors; Low-cost solution; Manufacture process; Monochromatic light; Photovoltaic devices; Planar structured; Quantum conversion efficiency; Bias voltagejournal article10.1021/acs.jpclett.5b00723