Fabrication of Quantum‐Dot Superlattices and Carrier Dynamics Depending on Controlled Interdot Distances

High‐density assemblies or superlattice (SL) structures composed of colloidal semiconductor quantum dots (QDs) are promising materials for advanced photonics devices due to their unique transport and optical properties. In QD SLs, quantum coupling between the localized energy states of periodically arranged QDs leads to the transformation of discrete energy states into continuous states known as “minibands” analogous to energy bands in atomic solids. Thin QD SL films are successfully fabricated using colloidal cadmium selenide QDs with an average diameter of ≈3 nm. Structural analysis reveals that QDs are arranged on the lattice points of a face‐centered cubic lattice, with single domain sizes estimated to be 70–90 nm. By modifying the alkyl‐chain lengths of amine ligands on the QD surfaces, the lattice constants of SLs are precisely controlled. Time‐resolved photoluminescence spectroscopy shows that recombination dynamics of excited carriers in the QD SLs are influenced by the spatial intervals between QDs. At larger intervals (>2.2 nm), resonant energy transfer (RET) due to long‐range dipole–dipole interaction is observed. In contrast, at smaller intervals (<2 nm), the behavior is different from that due to the RET, suggesting that quantum coupling between closely spaced QDs emerged.