We investigated a method of forming a perfect quantum dot (QD) superlattice, in which each QD has the same plane orientation, by depositing colloidal PbS QDs with clear facets in solution. QD facets were controlled by adjusting the synthesis temperature. X-ray evaluation showed that the crystal orientations of the film with QDs having clear facets were aligned. The slow deposition promoted this crystal alignment. The red shift of photoluminescence wavelength caused by the film formation was larger with QDs having facets than with spherical QDs, suggesting that the connection of the wave function between QDs was better so that the quantum size effect was further reduced.
We report the successful fabrication of a superlattice film composed of PbS colloidal quantum dots (QDs) with a three-dimensionally coincident crystal orientation. Faceted QDs with a truncated octahedral shape were prepared and deposited in a solvent on a pyramidal microhole array prepared on a Si (100) substrate. During the deposition, facets of neighboring QDs came into contact with each other in the aligned microholes.The three-dimensional crystal orientation alignment was confirmed by X-ray pole figure mapping. Such QD superlattice film with aligned crystal orientation can contribute to the realization of high-energy conversion efficiency of semiconductor solar cells.
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