(color online) (a) 3D schematic view of the triple-layer photodetector with monochromatic light beam.^[46] (b) The transfer curves of triple-layer channel with P(VDF-TrFE) ferroelectric polymer gate on dark state at room temperature. The transfer characteristics of triple-layer with back-gate are shown in the inset.^[46] (c) characteristics (at ZERO gate voltage) with three ferroelectric polarization states in the ferroelectric layer. The three states are: fresh state (ferroelectric layer without polarization), polarization up (“ ” polarized by a pulse of −40 V), and polarization down (“ ” polarized by a pulse of −40 V) states, respectively.^[46] (d) The cross section structures of the device and equilibrium energy band diagrams of ferroelectric polarization up state with V. is the bandgap of . is the height from bottom of conduction band to the Fermi level.^[46] (e) Photo switching behavior of ferroelectric polarization gating triple-layer photodetector at three states (λ = 635 nm, mV, and P = 100 nW).^[46] (f) Responsitivity of similar polarization-gating triple layer photodetector as a function of light wavelength from 500 nm to 1550 nm at V, P = 100 mW under state.^[46]