The lifetime and power conversion efficiency are the key issues for the commercialization of perovskite solar cells (PSCs). In this paper, the development of 2D/3D perovskite hybrids (CAPbI/MAPbICl) was firstly demonstrated to be a reliable method to combine their advantages, and provided a new concept for achieving both stable and efficient PSCs through the hybridization of perovskites. 2D/3D perovskite hybrids afforded significantly-improved moisture stability of films and devices without encapsulation in a high humidity of 63 ± 5%, as compared with the 3D perovskite (MAPbICl). The 2D/3D perovskite-hybrid film did not undergo any degradation after 40 days, while the 3D perovskite decomposed completely under the same conditions after 8 days. The 2D/3D perovskite-hybrid device maintained 54% of the original efficiency after 220 hours, whereas the 3D perovskite device lost all the efficiency within only 50 hours. Moreover, the 2D/3D perovskite hybrid achieved comparable device performances (PCE: 13.86%) to the 3D perovskite (PCE: 13.12%) after the optimization of device fabrication conditions.

Electron-beam-stimulated deposition and etching has been investigated as a clean, alternative method for nanoscale selective processing. Depositions using W(CO)6 and hydrocarbon sources have yielded efficient and selective electron-beam deposits. Primarily fluorine-based precursors have been used to etch a variety of materials. Initial results regarding the selective etching of silicon and silicon dioxide suggest that inelastic scattering of the primary electron beam with the gas occurs and is more severe at lower beam energies. The etch rate increases linearly with decreasing electron-beam energy, however, it is not clear if this is due to enhanced primary- or secondary-electron-stimulated processes. Feature sizes as small as 55 nm have been selectively processed.

We report a scalable method to fabricate high-quality graphene nanopores for biomolecule detection using a helium ion microscope (HIM). HIM milling shows promising capabilities for precisely controlling the size and shape, and may allow for the potential production of nanopores at wafer scale. Nanopores could be fabricated at different sizes ranging from 5 to 30 nm in diameter in few minutes. Compared with the current solid-state nanopore fabrication techniques, e.g. transmission electron microscopy, HIM is fast. Furthermore, we investigated the exposure-time dependence of graphene nanopore formation: the rate of pore expansion did not follow a simple linear relationship with exposure time, but a fast expansion rate at short exposure time and a slow rate at long exposure time. In addition, we performed biomolecule detection with our patterned graphene nanopore. The ionic current signals induced by 20-base single-stranded DNA homopolymers could be used as a basis for homopolymer differentiation. However, the charge interaction of homopolymer chains with graphene nanopores, and the conformations of homopolymer chains need to be further considered to improve the accuracy of discrimination.

A CE-LIF detection method has been developed to identify and quantitate six amino acid neurotransmitters including glutamic acid, aspartic acid, gamma-aminobutyric acid, glycine, taurine, and glutamine. N-hydroxysuccinimidyl fluorescein-O-acetate, a fluorescein-based dye, was employed for the derivatization of these neurotransmitters prior to CE-LIF analysis. Different parameters which influenced separation and derivatization were optimized in detail. Under optimum conditions, linearity was achieved within concentration ranges of up to three orders of magnitudes for those analytes with correlation coefficients from 0.9989 to 0.9998. The LODs ranged from 0.06 nM to 0.1 nM, and are thus superior or equivalent to those previously reported in the literature using CE-LIF detection. The proposed method has been successfully applied to the determination of amino acid neurotransmitters in biological samples such as human cerebrospinal fluid and saliva with satisfactory recoveries.