We report a novel orthogonal lithography fabrication of patterned inorganic perovskite CsPbX 3 (X= Cl, Br, I) quantum dot (QD) arrays which cannot be patterned with traditional approaches. This approach involves a combination of fluorinated polymer and solvent to resolve issues of polar-non-polar solvent constraints thus enabling the fabrication of complex patterns with high optical gain and bright and multicolor emission. We utilized this approach to fabricate high-resolution large-area arrays of microdisk lasers and milticolor (binary-and ternary-emission) pixels. The optical cavity modes of CsPbBr 3 QD microdisk lasers were readily controlled by tuning the disk size, where the mode spacing decreases while the number of modes increases with increasing disk diameter. Finally, we demonstrated the versatility of our approach for the integration of environmentally-sensitive QDs with different emission signatures and composition on the same chip, while achieving high density, highresolution large-area QD arrays with multicolor pixels.

Two-dimensional (2D) organic-inorganic hybrid perovskite multiple quantum wells that consist of multilayers of alternate organic and inorganic layers exhibit large exciton binding energies of order of 0.3 eV due to the dielectric confinement between the inorganic and organic layers. We have investigated the exciton characteristics of 2D butylammonium lead iodide, (CHNH)PbI using photoluminescence and UV-vis absorption in the temperature range of 10 K to 300 K, and electroabsorption spectroscopy. The evolution of an additional absorption/emission at low temperature indicates that this compound undergoes a phase transition at ≈250 K. We found that the electroabsorption spectrum of each structural phase contains contributions from both quantum confined exciton Stark effect and Franz-Keldysh oscillation of the continuum band, from which we could determine more accurately the 1s exciton, continuum band edge, and the exciton binding energy.

The growing demand for nonfossil fuel-based energy production has drawn attention to the utilization of natural proteins such as photosynthetic reaction center (RC) protein complexes to harvest solar energy. The current study reports on an immobilization method to bind the wild type Rhodobacter sphaeroides RC from the primary donor side onto a Au electrode using an immobilized cytochrome c (cyt c) protein via a docking mechanism. The new structure has been assembled on a Au electrode by layer-by-layer deposition of a carboxylic acid-terminated alkanethiol (HOOC (CH2)5S) self-assembled monolayer (SAM), and layers of cyt c and RC. The Au|SAM|cyt c|RC working electrode was applied in a three-probe electrochemical cell where a peak cathodic photocurrent density of 0.5 μA cm–2 was achieved. Further electrochemical study of the Au|SAM|cyt c|RC structure demonstrated ∼70% RC surface coverage. To understand the limitations in the electron transfer through the linker structure, a detailed energy study of the SAM and cyt c was performed using photochronoamperometry, ellipsometry, photoemission spectroscopy, and cyclic voltammetry (CV). Using a simple rectangle energy barrier model, it was found that the electrode work function and the large barrier of the SAM are accountable for the low conductance in the devised linker structure.

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Proper selection of the quantum dot ligand allows for controllable enhancement of optical gain characteristics (threshold, magnitude, and stability) in quantum dot films.