Composition and method comprising overcoated quantum dots

A coated quantum dot comprising:

• a type-I quantum dot with a single semiconductor shell of a thickness from 10 to 40 monolayers and having a core/shell structure selected from CdSe/Cd1-xZnxS, CdSe/Cd1-xZnxSe, CdSe/ZnSe1-ySy, CdSe/Cd1-xZnxSe1-ySy, CdTe/ZnSe1-ySy, CdTe/Cd1-xZnxSe1-ySy, CdSe1-xSx/Cd1-yZnyS, Cd1-xZnxSe/ZnSe1-ySy, InAs/CdSe, InAs/InP, InAs/Cd1-xZnxSe1-ySy, Cd3P2/ZnSe1-ySy, InxGa1-xP/ZnSe1-ySy, InxGa1-xP/GaP1-yNy, CuInSe2(1-x)S2x/ZnSe1-ySy, AgInSe2(1-x)S2x/ZnSe1-ySy, or (ZnSe)x(CuInSe2)1-x/ZnSe1-ySy and x is from greater than zero to less than 1, and y is from greater than zero to less than 1;
• and
• a silica coating having a thickness of from 3 nm to 20 nm, the silica coating containing only a single quantum dot;
• wherein the coated quantum dot has an improved photoluminescence lifetime and improved thermal stability compared to a type-I quantum dot having the same core/shell structure but without a silica coating.

A coated quantum dot comprising:

• a type-I quantum dot having a core/shell structure comprising a CdSe core and a single semiconductor shell, the single semiconductor shell having a structure Cd1-xZnxS where x is from greater than zero to less than 1, and a shell thickness of from 3 nm to 10 nm;
• and
• a silica coating having a thickness of from 5 nm to 20 nm, the silica coating containing only a single quantum dot;
• and wherein
• the coated quantum dot exhibits less than 10% decrease in a photoluminescence quantum yield after 200 hours in an accelerated aging test;
• the photoluminescence quantum yield of the coated quantum dot is reduced by 15% or less after 4 months of exposure to air and room lights from the photoluminescence intensity of the coated quantum dot prior to the 4 months exposure;
• and
• the photoluminescence quantum yield of the coated quantum dot is reduced by less than 10% after heating to 200° C.

A device, comprising:

• a substrate;
• and
• a thin film luminescent solar concentrator comprising a polymer and one or more coated quantum dots comprising
• a type-I quantum dot having a core/shell structure comprising a CdSe core and a single semiconductor shell, the single semiconductor shell having a structure Cd1-xZnxS where x is from greater than zero to less than 1, and a shell thickness of from 3 nm to 10 nm;
• and
• a silica coating having a thickness of from 5 nm to 20 nm, the silica coating containing only a single quantum dot;
• wherein
• the thin film luminescent solar concentrator exhibits less than 10% decrease in a photoluminescence quantum yield after 200 hours in an accelerated aging test;
• the photoluminescence quantum yield of the thin film luminescent solar concentrator is reduced by 15% or less after 4 months of exposure to air and room lights from the photoluminescence intensity of the thin film luminescent solar concentrator prior to the 4 months exposure;
• and
• the photoluminescence quantum yield of the thin film luminescent solar concentrator is reduced by less than 10% after heating to 200° C.