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In this study, a new configuration of dye sensitized solar cells (DSSCs), in which a TiO2 photoanode is co-sensitized by N719 organic dye and CdSe quantum dots (CdSe-QDs), was fabricated. The photovoltaic performance of the cell, which was co-sensitized with an optimum concentration of CdSe-QDs, was found to be superior to that of the cell with a photoanode sensitized using N719 dye. The superior performance can be attributed to the energy-compatible band structures of the N719 dye molecule and the CdSe-QDs, selective transfer of a significant number of photogenerated electrons from the energy state of the dye molecule to the conduction band (CB) of CdSe-QDs, and improved absorbance of the CdSe-QDs in the visible-light spectrum. This initial inflow of electrons to the dye was found to enrich the subsequent dye-mediated electron transfer to TiO2, thus contributing to the enhanced photocurrent in the DSSC. The novel material implemented in this study was based on CdSe-QDs, which were used as a co-sensitizer in the photoanode of the DSSC synthesized by pulsed laser ablation in liquid (PLAL). Morphological, structural, elemental, optical and electrochemical characterizations of the photoanodic materials were conducted; and the photovoltaic characteristics of the fabricated cell were determined. The photovoltaic conversion efficiency of the cell co-sensitized by CdSe-QDs at a certain concentration (1 mg/15 ml of ethanol) and N719 dye was found to be 7.09%, which corresponds to a 37% enhancement of the photovoltaic efficiency when compared with the cell sensitized only by the N719 dye.

Organometallic halide perovskite materials have gained enormous interest in energy conversion and various optoelectronics applications. These unique materials possess great ionic response. Hence, their suitability for energy storage device applications needs to be explored. We fabricated for the first time all-solid-state perovskite electrochemical supercapacitors with high areal capacitance, fast charge-discharge rate, high power density and superior cyclability. We investigated electrochemical energy storage performance of two different quasi-solid-state electrolytes sandwiched between two symmetric perovskite electrodes. We recorded highest areal capacitance of 21.50 μF/cm2 which is 3.65 times greater than areal capacitance recorded by similar perovskite electrochemical capacitors utilizing liquid-state electrolytes. High power density of 5.05 W/cm2 was achieved. Electrochemical impedance spectroscopy (EIS) was used to study the ionic transport mechanism and properties of our fabricated devices. The Nyquist plots exhibit linear characteristic across low and high frequency ranges, indicating excellent electrolytes diffusion into the perovskite electrodes and confirming ideal supercapacitor behavior of these devices. All devices exhibit short relaxation time with device having least relaxation time of 251.19 μs indicative of fast discharge properties of fabricated devices. Our devices show excellent cyclability with device retaining 98.34% of its initial capacitance after 1000 cycles.

Platinum (Pt) counter electrodes (CEs) have consistently shown excellent electrocatalytic performance and holds the record of the highest power conversion efficiency (PCE) for dye-sensitized solar cells (DSSCs). However, its use for large-scale production is limited either by high temperature required for thermal decomposition of its precursor or by wastage of the material leading to high cost or sophisticated equipment. Here, we report a novel photofabrication technique to fabricate highly transparent platinum counter electrodes by ultraviolet (UV) irradiation of platinic acid (H2PtCl6.6H2O) on rigid fluorine-doped tin oxide (FTO) and flexible indium-doped tin oxide (ITO) on polyethylene terephthalate (PET) substrates. The photofabrication technique is a facile and versatile method for the fabrication of Pt CEs for dye sensitized solar cells (DSSCs). The photofabricated Pt CEs were used to fabricate bifacial DSSCs with power conversion efficiencies (PCEs) attaining 7.29% for front illumination and 5.85% for rear illumination. The highest percentage ratio of the rear illumination efficiency to the front illumination efficiency (ηR) of 85.92% was recorded while the least ηR is 77.91%.

This paper presents the design and control of a high-speed and large-range atomic force microscopy (AFM). A multi-actuation scheme is proposed where several nano-positioners cooperate to achieve the range and speed requirements. A simple data-based control design methodology is presented to effectively operate the AFM scanner components. The proposed controllers compensate for the coupled dynamics and divide the positioning responsibilities between the scanner components. As a result, the multi-actuated scanner behavior is equivalent to that of a single X-Y-Z positioner with large range and high speed. The scanner of the designed AFM is composed of five nano-positioners, features 6 μm out-of-plane and 120 μm lateral ranges and is capable of high-speed operation. The presented AFM has a modular design with laser spot size of 3.5 μm suitable for small cantilever, an optical view of the sample and probe, a conveniently large waterproof sample stage and a 20 MHz data throughput for high resolution image acquisition at high imaging speeds. This AFM is used to visualize etching of calcite in a solution of sulfuric acid. Layer-by-layer dissolution and pit formation along the crystalline lines in a low pH environment is observed in real time.