Quantum Dot Light‐Emitting Transistors—Powerful Research Tools and Their Future Applications

Abstract

In this progress report, the recent work in the field of light-emitting field-effect transistors (LEFETs) based on colloidal quantum dots (CQDs) as emitters is highlighted. These devices combine the possibility of electrical switching, as known from field-effect transistors, with the possibility of light emission in a single device. The properties of field-effect transistors and the prerequisites of LEFETs are reviewed, before motivating the use of colloidal quantum dots for light emission. Recent reports on these quantum dot light-emitting field-effect transistors (QDLEFETs) include both materials emitting in the near infrared and the visible spectral range-underlining the great potential and breadth of applications for QDLEFETs. The way in which LEFETs can further the understanding of the CQD material properties-their photophysics as well as the carrier transport through films-is discussed. In addition, an overview of technology areas offering the potential for large impact is provided.channel is separated from the gate by an insulating gate dielectric. Gate electrode, dielectric, and channel form a capacitor that allows for charge accumulation at the channel-dielectric interface, through which the conductivity of the channel is modulated.Most commonly, the semiconducting material in the channel is doped and the FETs work through the conduction of either holes or electrons (unipolar FET). Such FETs are classified according to their working principle into inversion-mode or accumulation mode devices. For example, in n-channel inversion-mode FETs, the channel region is p-doped, and the source and drain regions are n-type semiconductors. By applying a positive gate voltage, the semiconductor at the interface with the gate dielectric inverts from p-type to n-type (inversion layer) and the channel becomes conductive. This mode is the most common operating mode of silicon metal-oxide-semiconductor FETs (MOSFET).The standard characterization of an FET includes the measurement of the output and the transfer characteristics. For the former, the gate voltage V G is constant, and the drain current I D Simon Kahmann received a shared doctorate degree from

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“…In this case, a large drain-source bias is used, inducing opposite carrier density (ie electron vs hole) for the drain and source electrodes. This mode has been extensively used to design gate-induced light emitting diodes, [42][43][44][45] in particular in organic compounds. [46][47][48] In this paper, we demonstrate that graphene-based electrodes combined with ionic glass gating offer an interesting platform for the design of gate-induced 2D/0D p-n junction.…”

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“…The hole transport ability of an OLET can be characterized by the carrier mobility and the threshold voltage ( V TH ). The hole mobility is derived from the transfer curves in the saturation region by the following equation [ 31 ] where W and L represent the channel width and length, respectively, and C i is the capacitance per unit area of the dielectric (≈4.5 nF cm −2 ). The threshold voltage can be determined from the relationship between and V GS as shown in Figure S7 in the Supporting Information.…”

“…The hole transport ability of an OLET can be characterized by the carrier mobility and the threshold voltage (V TH ). The hole mobility is derived from the transfer curves in the saturation region by the following equation [31] L wc…”

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