A method comprising: depositing a quantum dot solution onto a supporting substrate in a drop-wise manner to form one or more discrete droplets on a surface of the substrate, the quantum dot solution and discrete droplets comprising a plurality of quantum dots having primary ligands attached thereto to stabilize the quantum dots in solution; and depositing a ligand-exchange solution onto the one or more discrete droplets in a drop-wise manner to cause replacement of the primary ligands attached to the plurality of quantum dots with shorter-chain secondary ligands, replacement of the primary ligands with the secondary ligands allowing the plurality of quantum dots within each discrete droplet to become sufficiently close packed to facilitate charge transfer there between.