We demonstrate improved compatibility of poly(ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) hole transport layer with acid-sensitive materials by addition of a simple base, NaOH or NH4OH, to the aqueous suspension to increase pH. Addition of NaOH to the acidic PEDOT:PSS allowed the deposition of PEDOT:PSS on top of an inverted poly(3-hexylthiophene):ZnO nanoparticle blend hybrid photovoltaic device, and improved device performance due to preservation of the ZnO electron acceptor. To quantitatively investigate the impact of base addition to hole transport layer properties and device performance, we deposited PEDOT:PSS with different pH values on inverted poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester bulk heterojunction devices. We find that NaOH modification results in a substantial work function decrease and series resistance increase. In contrast, the volatile NH4OH leaves PEDOT:PSS with minimal changes in film properties and device performance.

The interfacial energies between template-directed calcite nuclei and self-assembled monolayers of 16-mercaptohexadecanoic acid (MHA) and 11-mercaptoundecanoic acid (MUA) were measured. The results reveal that (1) the MHA and MUA significantly reduce the effective surface energy of calcite from about 97 mJ/m2 in solution to about 45.3 and 52.7 mJ/m2 on MHA and MUA respectively, providing a thermodynamic basis for the strong capacity of MHA and MUA to promote calcite nuclei; and (2) the barrier to nucleation is dominated by the free energy barrier which enhances the rate of surface nucleation on MHA and MUA.

In this work, we report the synthesis and characterization of three dimensional heterostructures graphene nanostructures (HGN) comprising continuous large area graphene layers and ZnO nanostructures, fabricated via chemical vapor deposition. Characterization of large area HGN demonstrates that it consists of 1-5 layers of graphene, and exhibits high optical transmittance and enhanced electrical conductivity. Electron microscopy investigation of the three dimensional heterostructures shows that the morphology of ZnO nanostructures is highly dependent on the growth temperature. It is observed that ordered crystalline ZnO nanostructures are preferably grown along the <0001> direction. Ultraviolet spectroscopy indicates that the CVD grown HGN layers has excellent optical properties. A combination of electrical and optical properties of graphene and ZnO building blocks in ZnO based HGN provides unique characteristics for opportunities in future optoelectronic devices.

A robust, stable and thin primary amine functionalization is applied to gold and silver nanoparticles from poly(allylamine hydrochloride) (PAH) by converting a fraction of the amine groups in the polymer to dithiocarbamate (DTC) ligands, which absorb strongly onto noble metal surfaces. We observe marked improvements in the properties of gold nanospheres with a DTC-anchored rather than physisorbed PAH cap. The same level of improvement is not seen in silver nanoparticles, although it is clear from a distinct change in the plasmon spectrum in silver nanocubes that the DTC ligand does interact with the silver surface. In spite of their amine functionalization, both silver and gold particles show low cytotoxicity, possibly due to absorption of serum proteins forming a protective coating on the positively charged particle surface.

This paper describes the principle of array sensing with film bulk acoustic resonators (FBARs) for combinatory mass sensing and the use of the arrayed FBAR resonant mass sensor for parallel detection of protein-ligand reactions in liquid environment. Various ligands were immobilized on the gold layer on the FBAR’s sensing surface for selective protein detection. The FBARs of the arrayed FBAR were fabricated to have different resonant frequencies from one another by adding slightly varied amount of mass loading on the resonators. Results showed that the arrayed FBAR could detect specific bindings on its surfaces as the concentration of the target ligand was varied.

We demonstrated the enhancement of electroluminescence (EL) from green CdSe/ZnS QDs in hybrid QD/organic light-emitting diodes (QD-LEDs) by employing blue phosphorescent dyes Bis(4,6-difluorophenylpyridinato-N,C2)picolinatoiridium (FIrpic) as efficient exciton harvesters and energy transfer donors. Precise control of the concentration of the FIrpic donors doped in a 4,4’-N, N’-dicarbazole-biphenyl (CBP) host and their distance from the QD layer led to complete triplet exciton energy transfer and EL enhancement by a factor of 2.5. The Förster distance between FIrpic molecules and green CdSe/ZnS QDs was determined to be ∼ 8 nm, which is in a good agreement with the value calculated using the Förster model. Our study shows that integrating colloidal QDs with phosphorescent organic dyes provides an effective means for improving the quantum efficiency of QD-based hybrid LEDs.