Air stable infrared photodetectors from solution-processed inorganic semiconductors

A method of preparing a photodetector comprising a photoactive layer comprising semiconducting inorganic nanoparticles, a hole transport layer comprising a first metal oxide, an electron transport layer comprising a second metal oxide, wherein the semiconducting inorganic nanoparticles are responsive to electromagnetic radiation in at least the infrared region of the spectrum, wherein the photoactive layer is positioned between the hole transport layer and the electron transport layer, and is in direct contact with the electron transport layer, wherein the photodetector is stable in air in the absence of an external encapsulating coating, the method comprising:

• providing a substrate comprising an electrode;
• depositing a first solution of a first metal oxide precursor or a first suspension of a plurality of metal oxide particles on the electrode;
• removing the solvent from the first solution or first suspension to form a first layer comprising the first metal oxide;
• depositing a colloidal suspension of semiconducting inorganic nanoparticles on the first layer;
• removing the solvent from the colloidal suspension of semiconducting inorganic quantum dots to form a photoactive layer comprising semiconducting inorganic quantum dots;
• depositing a second solution of a second metal oxide precursor or a second suspension of a plurality of metal oxide particles on the photoactive layer;
• and
• removing the solvent from the second solution or second suspension to form a second layer comprising the second metal oxide.