Light-emitting field-effect transistors combining organic and metal oxide layers with partitioned heterogeneous source and drain electrodes

Abstract

We fabricated organic light-emitting field-effect transistors (OLEFETs) characterized by partitioned heterogeneous source and drain contacts along with an aluminum-doped zinc oxide (AZO) layer inserted between an organic layer and a gate insulator. We elaborated such contacts so that each contact was made of a metal(s) suitable for injecting either electrons or holes. We fabricated the devices by choosing two of three kinds of metals (Au, Al, and MgAg) and one of three organic semiconductor materials. In the devices with the Au source and MgAg drain contacts, we observed drain currents at both positive and negative drain voltages. Those currents were predominant at negative drain voltages in the devices with Al drain contacts. The most intense current-injected emissions arose from the vicinity of the electron injection contact edges near channels on the AZO layers. Taking into account the energy level consideration of the materials and the effect of the partitioned contacts, we discussed these electrical and emission properties.

Orange‐Red‐Light‐Emitting Field‐Effect Transistors Based on Phosphorescent Pt(II) Complexes with Area Emission

“…So far the majority of emissive materials used in organic LEFETs have been fluorescent. [12][13][14][15] The major drawback many fluorescent materials have, is that they only emit from singlet excitons, which leaves up to 75% of the input current (i.e., those that form triplet excitons) wasted, as the triplet excitons in fluorescent materials are non-radiative, thus leading to poorer device performance. The use of phosphorescent materials allows for harnessing both singlet and triplet excitons generated in LEFETs due to efficient inter-system crossing and a high radiative decay rate for the triplet exciton.…”

Organic Semiconductor Single‐Crystal Light‐Emitting Transistors

“…The current density of OSSCLETs has significantly improved in recent years, with a maximum current density of 325.6 kA cm −2 , based on the assumption that charge is transferred within only one molecular layer (Figure 6). [8,38,46,48,54,60,[63][64][65]83,[97][98][99][100][101][102] Owing to their combination of charge transport and strong emission properties, high-mobility emissive materials are ideal candidates for the construction of highly efficient OSSCLET devices. In Figure 2c, a series of high-mobility emissive organic semiconductors for the construction of OSSCLET devices is described.…”

“…The current density of OSSCLETs has significantly improved in recent years, with a maximum current density of 325.6 kA cm −2 , based on the assumption that charge is transferred within only one molecular layer ( Figure ). [ 8,38,46,48,54,60,63–65,83,97–102 ]…”

Organic crystal light-emitting transistors with top-gate configuration

“…9,[17][18][19][20] Under these circumstances, we developed OLETs in which a p-type organic semiconductor thin film was combined with an aluminum-doped zinc oxide (AZO). 21,22) AZO is an n-type metal oxide semiconductor and its carrier density (∼10 20 cm −3 ) 23,24) is much higher than that of the organic semiconductors. 25) The organic thin film covered a patterned AZO layer that was located on a gate insulator layer.…”

“…These devices showed intense emissions near hole-injection contacts under applied positive and negative DC voltages of ∼20-100 V to the holeand electron-injection contacts, respectively, with the gate contact grounded. 21,22) Then, we fabricated related devices by replacing the organic thin film with an organic crystal. 26) Although the crystal devices showed current-injected light emissions from the channel zone, we needed to apply voltages of ∼30-90 V. 26) The above-mentioned devices had the bottom-gate and top-contact configuration.…”