# US 9,006,726 B2 · Organic light emitting ambipolar field effect transistor with distributed light emission

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 9,006,726 B2
- Document ID: US9006726B2
- Status: Granted
- Kind: B2
- Application number: 14/373,225
- Filed: 2013-02-21
- Published: 2015-01-01
- Granted: 2015-04-14
- Earliest claimed: 2012-02-27
- Assignees: E.T.C. S.R.L.
- Applicants: E.T.C. S.R.L.
- Inventors: Raffaella Capelli; Gianluca Generali; Michele Muccini; Stefano Toffanin
- Web page: https://patentgrep.com/patent/US9006726B2

## CPC

- H10K 50/30: Organic light-emitting transistors
- H10K 50/11: characterised by the electroluminescent [EL] layers
- H10K 50/12: comprising dopants
- H10K 71/311: {Purifying organic semiconductor materials}
- H10K 85/324: {comprising aluminium, e.g. Alq3}
- H10K 85/346: {comprising platinum}
- H10K 85/655: {comprising only sulfur as heteroatom}
- H10K 2101/30: Highest occupied molecular orbital [HOMO], lowest unoccupied molecular orbital [LUMO] or Fermi energy values
- H10K 2101/40: Interrelation of parameters between multiple constituent active layers or sublayers, e.g. HOMO values in adjacent layers
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES

## Abstract

An organic ambipolar light emitting field effect transistor having an architecture with layers stacked one over the other, adapted to generate a diffused illumination is described. The transistor has a gate electrode, a dielectric layer superposed to the gate electrode, an ambipolar channel superposed to the dielectric layer having a P-type semiconductor layer whose energy band is determined by its highest occupied molecular orbital HOMO-SCp and lowest unoccupied molecular orbital LUMO-SCp, a N-type semiconductor layer whose energy band is determined by its highest occupied molecular orbital HOMO-SCn and lowest unoccupied molecular orbital LUMO-SCn and a light emitting layer adapted to allow recombination of charge carriers of opposite sign, interposed between the P-type semiconductor layer and the N-type semiconductor layer, whose energy band is determined by its highest occupied molecular orbital HOMO-R and lowest unoccupied molecular orbital LUMO-R, respectively; a source electrode adapted to inject charges of a first type and a drain electrode adapted to inject charges of a second type, said source electrode and drain electrode being in contract with a same layer of said P-type or N-type semiconductor layers, the other of said semiconductor layers being in contact with the dielectric layer.

## Claims

### Claim 1

An electroluminescent ambipolar organic field-effect transistor, having an architecture with stacked layers, comprising:
a gate electrode,
a dielectric layer superposed to said gate electrode,
an ambipolar channel superposed to said dielectric layer, comprising
a P-type semiconductor layer whose energy band is determined by its highest occupied molecular orbital HOMO-SCp and lowest unoccupied molecular orbital LUMO-SCp,
an N-type semiconductor layer (SCn) whose energy band is determined by its highest occupied molecular orbital HOMO-SCn and lowest unoccupied molecular orbital LUMO-SCn, and
a light emitting layer adapted to allow recombination of charge carriers of opposite sign, interposed between said P-type semiconductor layer and said N-type semiconductor layer, said light emitting layer being alternatively composed of either a single material whose energy band is determined by its highest occupied molecular orbital HOMO-R and lowest unoccupied molecular orbital LUMO-R, or a Host-Guest system composed of a Host material and one or more Guest materials, the Host material having an energy band determined by its highest occupied molecular orbital HOMO-H and lowest unoccupied molecular orbital LUMO-H and the one or more Guest materials having each an energy band determined by respective highest occupied molecular orbital HOMO-G and lowest unoccupied molecular orbital LUMO-G,
a source electrode adapted to inject charges of a first type and
a drain electrode adapted to inject charges of a second type, said source electrode and drain electrode being in contact with a top layer of said P-type or N-type semiconductor layers, a bottom layer of said P-type or N-type semiconductor layers being in contact with the dielectric layer, wherein
a ratio between a value of an effective field-effect mobility at an interface between the top layer of said P-type or N-type semiconductor layers and said light emitting layer and a value of an effective field-effect mobility at an interface between the bottom layer of said P-type or N-type semiconductor layers and said dielectric layer is in the range from 0.05 to 20;
in the case in which the P-type semiconductor layer is in contact with the dielectric layer and said light emitting layer is composed of a single material:
the difference between the levels HOMO-R and HOMO-SCn is comprised between 0.2 eV and 1 eV,
the difference between the levels LUMO-R and LUMO-SCn is comprised between 0.2 eV and 0.8 eV,
the difference between the levels HOMO-R and HOMO-SCp is comprised between 0 eV and 0.5 eV,
the difference between the levels LUMO-R and LUMO-SCp is comprised between −1 eV and 0 eV;
in the case in which the N-type semiconductor layer is in contact with the dielectric layer and said light emitting layer is composed of a single material:
the difference between the levels HOMO-R and HOMO -SCn is comprised between 0 eV and 1 eV,
the difference between the levels LUMO-R and LUMO-SCn is comprised between −0.5 eV and 0 eV,
the difference between the levels HOMO-R and HOMO-SCp is comprised between −0.2 eV and −0.8 eV,
the difference between the levels LUMO-R and LUMO-SCp is comprised between −0.2 eV and −1 eV;
in the case in which the P-type semiconductor layer is in contact with the dielectric layer and said light emitting layer is composed of a Host-Guest system:
the difference between the levels HOMO-H and HOMO-SCn is comprised between 0.2 eV and 1 eV,
the difference between the levels LUMO-H and LUMO-SCn is comprised between 0.2 eV and 3 eV,
the difference between the levels HOMO-H and HOMO-SCp is comprised between 0 eV and 0.5 eV,
the difference between the levels LUMO-H and LUMO-SCp is comprised between −1 eV and 3 eV, and
for all Guest materials:
the difference between the levels LUMO-G and LUMO-SCn is comprised between 0.3 eV and −1 eV,
the difference between the levels HOMO-G and HOMO-H is comprised between 0 eV and 1 eV;
in the case in which the N-type semiconductor layer is in contact with the dielectric layer and said light emitting layer is composed of a Host-Guest system:
the difference between the levels HOMO-H and HOMO-SCn is comprised between −3 eV and 1 eV,
the difference between the levels LUMO-H and LUMO-SCn is comprised between −0.5 eV and 0 eV,
the difference between the levels HOMO-H and HOMO-SCp is comprised between −0.2 eV and −3 eV,
the difference between the levels LUMO-H and LUMO-SCp is comprised between −0.2 eV and −1 eV, and
for all Guest materials:
the difference between the levels HOMO-G and HOMO-SCp is comprised between −0.3 eV and 1 eV, and
the difference between the levels LUMO-G and LUMO-H is comprised between 0 eV and −1 eV.

### Claim 2 (depends on 1)

The transistor according to claim 1, wherein said ratio is in the range from 0.7 to 1.3.

### Claim 3 (depends on 1)

The transistor according to claim 1, wherein the value of said effective field effect mobility at the interface between the top layer of said P-type or N-type semiconductor layers and said light emitting layer and the value of the effective field-effect mobility at the interface between the bottom layer of said P-type or N-type semiconductor layers and said dielectric layer are at least 10−3 cm2/Vs.

### Claim 4 (depends on 1)

The transistor according to claim 1, wherein a distance between said source electrode and drain electrode is between 20 μm and 300 μm.

### Claim 5 (depends on 1)

The transistor according to claim 1, wherein a surface roughness at the interfaces between said light emitting layer and each of the P-type or N-type semiconductor layers is in the range from 0.2 nm to 10 nm.

### Claim 6 (depends on 5)

The transistor according to claim 5, wherein said surface roughness is in the range from 0.2 nm to 5 nm.

### Claim 7 (depends on 1)

The transistor according to claim 1, wherein the materials forming said ambipolar channel have a purity between 99.8% and 99.999%.

### Claim 8 (depends on 7)

The transistor according to claim 7, wherein said purity is between 99.99% and 99.999%.

### Claim 9 (depends on 1)

The transistor according to claim 1, wherein said source electrode and rain electrode are made of a same material.

### Claim 10 (depends on 1)

The transistor according to claim 1, wherein in the case in which the P-type semiconductor layer is in contact with the dielectric layer and said light emitting layer is composed of a single material:
the difference between the levels LUMO-R and LUMO-SCn is comprised between 0.2 eV and 0.6 eV,
the difference between the levels HOMO-R and HOMO-SCp is comprised between 0.2 eV and 0.5 eV, and
the difference between the levels LUMO-R and LUMO-SCp is comprised between −1 eV and −0.2 eV;
in the case in which the N-type semiconductor layer is in contact with the dielectric layer and said light emitting layer is composed of a single material:
the difference between the levels HOMO-R and HOMO-SCn is comprised between 0.2 eV and 1 eV,
the difference between the levels LUMO-R and LUMO-SCn is comprised between −0.5 eV and −0.2 eV, and the difference between the levels HOMO-R and HOMO-SCp is comprised between −0.2 eV and −0.6 eV.