Semiconductor nanocrystals and method of preparation
View Patent ↗A method for preparing semiconductor nanocrystals comprising indium arsenide is disclosed. The method includes heating a first mixture including nanocrystal seeds comprising indium arsenide with an absorbance in a range from about 700 to 800 nm and a liquid medium in a reaction vessel to a first temperature; and combining the nanocrystals seeds comprising indium arsenide with an indium-source mixture and an arsenic-source mixture under conditions suitable to increase the size of the seeds to form the semiconductor nanocrystals comprising indium arsenide, wherein the indium-source mixture includes an indium precursor, a coordinating solvent, and a carboxylic acid; and the arsenic-source mixture includes a liquid medium and an arsenic precursor represented by the formula As(Y(R) 3 ) 3 , where Y is Ge, Sn, or Pb; and each R, independently, is alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, heterocyclyl, aryl, or heteroaryl, wherein each R, independently, is optionally substituted by 1 to 6 substituents independently selected from hydrogen, halo, hydroxy, nitro, cyano, amino, alkyl, cycloalkyl, cycloalkenyl, alkoxy, acyl, thio, thioalkyl, alkenyl, alkynyl, cycloalkenyl, heterocyclyl, aryl, or heteroaryl. Semiconductor nanocrystals are also disclosed.
1. A method for preparing semiconductor nanocrystals comprising indium arsenide, the method comprising:
heating a first mixture including nanocrystal seeds comprising indium arsenide with an absorbance in a range from about 700 to 800 nm and a liquid medium in a reaction vessel to a first temperature; and
combining the nanocrystals seeds comprising indium arsenide with an indium-source mixture and an arsenic-source mixture under conditions suitable to increase the size of the seeds to form the semiconductor nanocrystals comprising indium arsenide,
wherein the indium-source mixture includes an indium precursor, a coordinating solvent, and a carboxylic acid; and the arsenic-source mixture includes a liquid medium and an arsenic precursor represented by the formula (I):
As(Y(R) 3 ) 3 (I)
where Y is Ge, Sn, or Pb; and each R, independently, is alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, heterocyclyl, aryl, or heteroaryl, wherein each R, independently, is optionally substituted by 1 to 6 substituents independently selected from hydrogen, halo, hydroxy, nitro, cyano, amino, alkoxy, acyl, thio, and thioalkyl.
2. A method in accordance with claim 1 wherein the compound of formula (I) comprises tris(trimethylgermyl)arsine.
3. A method in accordance with claim 1 wherein the carboxylic acid comprises acetic acid.
4. A method in accordance with claim 1 wherein the carboxylic acid comprises oleic acid.
5. A method in accordance with claim 1 wherein the coordinating solvent comprises trioctylphosphine.
6. A method in accordance with claim 1 wherein the first temperature is in a range from about 160° C. to about 200° C.
7. A method in accordance with claim 1 wherein the mixture is heated to a second temperature is in a range from about 180° C. to about 220° C.
8. A method in accordance with claim 1 wherein the mixture is heated to a third temperature is in a range from about 260° C. to about 285° C.
9. A method in accordance with claim 1 wherein the arsenic-source mixture is added to the reaction vessel including the nanocrystal seeds at a controlled rate of addition and the indium-source mixture is added as one or more discrete additions, one being added before the addition of the arsenic-source mixture is initiated.
10. A method in accordance with claim 1 wherein the semiconductor nanocrystals comprising indium arsenide emit light at a wavelength in a range of 800 to 1200 nm.
11. A method in accordance with claim 1 wherein the indium precursor comprises an indium carboxylate.
12. A method in accordance with claim 1 wherein the indium precursor comprises indium myristate.
13. A method in accordance with claim 1 wherein the semiconductor nanocrystals comprising indium arsenide emit light with a half width at half maximum of less than 0.100 eV.
14. A method in accordance with claim 1 wherein a growth of the nanocrystal seeds is carried out in the absence of an amine.