# US 2014/0150861 A1 · Secondary treatment of films of colloidal quantum dots for optoelectronics and devices produced thereby

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- Number: US 2014/0150861 A1
- Document ID: US20140150861A1
- Status: Published application
- Kind: A1
- Application number: 14/176,254
- Filed: 2014-02-10
- Published: 2014-06-05
- Earliest claimed: 2011-07-20
- Assignees: Alliance for Sustainable Energy, LLC
- Applicants: Alliance for Sustainable Energy, LLC
- Inventors: Octavi Escala SEMONIN; Joseph M. LUTHER; Matthew C. BEARD; Hsiang-Yu CHEN
- Web page: https://patentgrep.com/patent/US20140150861A1

## CPC

- H10F 77/1433: {Quantum dots}
- B82Y 20/00: Nanooptics, e.g. quantum optics or photonic crystals
- H10F 10/162: comprising only Group II-VI materials, e.g. CdS/CdTe photovoltaic cells
- H10F 71/1257: {comprising growth substrates not made of Group II-VI materials}
- H10F 77/146: {Superlattices; Multiple quantum well structures}
- H10P 14/265: {using solutions}
- H10P 14/2922: {being non-crystalline insulating materials, e.g. glass or polymers}
- H10P 14/3226: {Oxides}
- H10P 14/3241: {being conductive materials}
- H10P 14/3248: {consisting of two layers}
- H10P 14/3402: {characterised by the chemical composition}
- H10P 14/3436: {being chalcogenide semiconductor materials not being oxides, e.g. ternary compounds}
- H10P 14/3461: {Nanoparticles}
- Y02E 10/543: Solar cells from Group II-VI materials
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A method of forming an optoelectronic device. The method includes providing a deposition surface and contacting the deposition surface with a ligand exchange chemical and contacting the deposition surface with a quantum dot (QD) colloid. This initial process is repeated over one or more cycles to form an initial QD film on the deposition surface. The method further includes subsequently contacting the QD film with a secondary treatment chemical and optionally contacting the surface with additional QDs to form an enhanced QD layer exhibiting multiple exciton generation (MEG) upon absorption of high energy photons by the QD active layer. Devices having an enhanced QD active layer as described above are also disclosed.

## Claims

### Claim 1

A method of forming an optoelectronic device comprising:
providing a deposition surface;
contacting the deposition surface with a ligand exchange chemical and contacting the deposition surface with a quantum dot (QD) colloid over one or more cycles to form an initial QD film on the deposition surface; and
contacting the QD film with a secondary treatment chemical.

### Claim 2 (depends on 1)

The method of forming an optoelectronic device of claim 1 wherein the step of contacting the initial QD film with a secondary treatment chemical comprises contacting the initial QD film with a secondary treatment chemical and contacting the deposition surface with a quantum dot (QD) colloid over one or more cycles to deposit additional QDs on the initial QD film.

### Claim 3 (depends on 2)

The method of forming an optoelectronic device of claim 2 wherein the secondary treatment chemical is at least one of hydrazine, formic acid, mercaptopropionic acid, an organic acid, methylamine, methanol, ethanol and ethylenediamine.

### Claim 4 (depends on 2)

The method of forming an optoelectronic device of claim 2 wherein the initial QD film is formed to a thickness of about 40 nm to 400 nm.

### Claim 6 (depends on 2)

The method of forming an optoelectronic device of claim 2 wherein the initial QD film is thickened by about 1 nm to 50 nm by the deposition of additional QDs in the secondary treatment step.

### Claim 7 (depends on 1)

The method of forming an optoelectronic device of claim 1 wherein the step of contacting the initial QD film with a secondary treatment chemical comprises contacting the initial QD film with a secondary treatment chemical over one or more cycles without depositing additional QDs on the QD film.

### Claim 8 (depends on 7)

The method of forming an optoelectronic device of claim 7 wherein the secondary treatment chemical is at least one of hydrazine, formic acid, mercaptopropionic acid, an organic acid, methylamine, methanol, ethanol and ethylenediamine.

### Claim 9

A method of forming a solar cell comprising:
providing a substrate;
forming a first electrode in contact with the substrate;
contacting the first electrode with a ligand exchange chemical and contacting the first electrode with a quantum dot (QD) colloid over one or more cycles to form an initial QD film in contact with the first electrode;
contacting the initial QD film with a secondary treatment chemical; and
forming a second electrode in contact with the initial QD film, not in contact with the first electrode.

### Claim 10 (depends on 9)

The method of forming a solar cell of claim 9 wherein the step of contacting the initial QD film with a secondary treatment chemical comprises contacting the initial QD film with a secondary treatment chemical and contacting the deposition surface with a quantum dot (QD) colloid over one or more cycles to deposit additional QDs on the initial QD film.

### Claim 11 (depends on 10)

The method of forming a solar cell of claim 10 wherein the secondary treatment chemical is at least one of hydrazine, formic acid, mercaptopropionic acid, an organic acid, methylamine, methanol, ethanol and ethylenediamine.

### Claim 12 (depends on 10)

The method of forming a solar cell of claim 10 wherein the initial QD film is formed to a thickness of about 40 nm to 400 nm.

### Claim 13 (depends on 10)

The method of forming a solar cell of claim 10 wherein the initial QD film is thickened by about 1 nm to 50 nm by the deposition of additional QDs in the secondary treatment step.

### Claim 14 (depends on 9)

The method of forming a solar cell of claim 9 wherein the step of contacting the initial QD film with a secondary treatment chemical comprises contacting the QD film with a secondary treatment chemical over one or more cycles without depositing additional QDs on the QD film.

### Claim 15 (depends on 14)

The method of forming a solar cell of claim 14 wherein the secondary treatment chemical is at least one of hydrazine, formic acid, mercaptopropionic acid, an organic acid, methylamine, methanol, ethanol and ethylenediamine.

### Claim 16 (depends on 9)

The method of forming a solar cell of claim 9 further comprising forming a doped window layer in contact with the first electrode and the initial QD film.

### Claim 17

A solar cell comprising:
a first electrode;
a QD active layer in electrical contact with the first electrode providing for multiple exciton generation (MEG) upon absorption of photons by the QD active layer; and
a second electrode in electrical contact with the QD active layer.

### Claim 18 (depends on 17)

The solar cell of claim 17 further comprising a doped window layer in electrical contact with the first electrode and the QD active layer.

### Claim 19 (depends on 17)

The solar cell of claim 17 wherein the QD active layer comprises at least one of QDs of lead selenide (PbSe), lead sulfide (PbS), cadmium selenide (CdSe), other semiconductor nanocrystals (NCs), core-shell and ternary nanocrystals, for example lead telluride (PbTe), lead selenide sulfide (PbSSe), lead selenide core with lead sulfide shell, cadmium lead sulfide (CdPbS), cadmium lead selenide (CdPbSe) tin sulfide (SnS), tin selenide (SnSe), tin telluride (SnTe), silicon (Si), germanium (Ge), indium arsenide (InAs), indium phosphide (InP), indium antimonide (InSb), gallium arsenide (GaAs), indium gallium arsenide (InGaAs) and NC structures of all other Group IV, II-VI, IV-VI compounds and alloys.

### Claim 20 (depends on 19)

The solar cell of claim 19 further comprising a glass substrate.