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Abstract BiVO4, a narrow bandgap material (2.5 eV), has been widely explored for photocatalytic applications, but its applications in the optoelectronic field are unexplored. This work explores BiVO4 for photovoltaic devices using the oxygen vacancies mediated co‐sputtered Ti‐doped BiVO4 (Ti:BiVO4) that exhibits on‐site power production by photovoltaics and see‐through features. The structural, chemical, and optical properties of Ti:BiVO4 are investigated for heterojunction formation with p‐type NiO film. The sputtering power of Ti plays a significant role in improving the light absorption capability by increasing oxygen vacancy concentration, enhancing the device performance. The devices show an open‐circuit voltage value of 676 mV and a short‐circuit current density value of 4.83 mA cm−2 with a maximum power production value of 122.2 µW under UV illumination of intensity 53.1 mW cm−2. The obtained device performances correlate with the Ti dopant's deposition power that tunes the structural and optical properties of BiVO4 films. Moreover, in self‐powered mode, the fabricated devices show a fast photoresponse speed of 0.8 ms with a high detectivity value of 2.22 × 1012 Jones. This work establishes the suitability of co‐sputtered Ti:BiVO4 for the next generation of transparent self‐powered optoelectronic devices.

High-power and lightweight photovoltaic (PV) modules are suitable for building-integrated photovoltaic (BIPV) systems. Due to the characteristics of the installation sites, the BIPV solar modules are limited by weight and installation area. In this study, we fabricated glass-free and shingled-type PV modules with an area of 1040 mm × 965 mm, which provide more conversion power compared to conventional PV modules at the same installed area. Further, we employed an ethylene tetrafluoroethylene sheet instead of a front cover glass and added an Al honeycomb sandwich structure to enhance the mechanical stability of lightweight PV modules. To optimize the conversion power of the PV module, we adjusted the amount of dispensed electrically conductive adhesives between the solar cells. Finally, we achieved a conversion power of 195.84 W at an area of 1.004 m2, and we performed standard reliability tests using a PV module that weighed only 9 kg/m2.

Interference lithography is a promising method for fabricating large-area, defect-free three-dimensional photonic crystal structures which can be used for facilitating the realization of photonic devices with a fast processing time. Although they can be used in waveguides, resonators, and detectors, their repeated regular array patterns can only be used for limited applications. In this study, we demonstrate a method for fabricating large-area photonic crystal structures with controlled defects by combining interference lithography and two-photon lithography using a light-curable resin. By combining regular array structures and controlled patterns, monotonous but large-area regular structures can be obtained. Furthermore, the patterned structures have considerable potential for use in various applications, such as solar cells, sensors, photodetectors, micro-/nano-electronics, and cell growth.

Transparent p-CuI/n-SiZnSnO (SZTO) heterojunction diodes are successfully fabricated by thermal evaporation of a (111) oriented p-CuI polycrystalline film on top of an amorphous n-SZTO film grown by the RF magnetron sputtering method. A nitrogen annealing process reduces ionized impurity scattering dominantly incurred by Cu vacancy and structural defects at the grain boundaries in the CuI film to result in improved diode performance; the current rectification ratio estimated at ±2 V is enhanced from ≈106 to ≈107. Various diode parameters, including ideality factor, reverse saturation current, offset current, series resistance, and parallel resistance, are estimated based on the Shockley diode equation. An energy band diagram exhibiting the type-II band alignment is proposed to explain the diode characteristics. The present p-CuI/n-SZTO diode can be a promising building block for constructing useful optoelectronic components such as a light-emitting diode and a UV photodetector.

We report the effects of H2S passivation on the effective minority carrier lifetime of crystalline silicon (c-Si) wafers. c-Si wafers were thermally annealed under an H2S atmosphere at various temperatures. The initial minority carrier lifetime (6.97 μs) of a c-Si wafer without any passivation treatments was also measured for comparison. The highest minority carrier lifetime gain of 2030% was observed at an annealing temperature of 600 °C. The X-ray photoelectron spectroscopy analysis revealed that S atoms were bonded to Si atoms after H2S annealing treatment. This indicates that the increase in minority carrier lifetime originating from the effect of sulfur passivation on the silicon wafer surface involves dangling bonds.

Effective incident light should be controlled for improving the current density of solar cells by employing nano- and micro-structures on silicon surface. The elastomeric stamp process, which is more cost effective and simpler than conventional photolithography, was proposed for the fabrication of nano- and micro-structures. Polydimethylsiloxane (PDMS) was poured on a mother pattern with a diameter of 6 μm and a spacing of 2 μm; then, curing was performed to create a PDMS mold. The regular micropattern was stamped on a low-viscosity resin-coated silicon surface, followed by the simple reactive ion etching process. Nano-structures were formed using the Ag-based electroless etching process. As etching time was increased to 6 min, reflectance decreased to 4.53% and current density improved from 22.35 to 34.72 mA/cm2.

It is beneficial to reduce thickness of high-purity of c-Si wafer for cost-effective water splitting system based on silicon photoelectrode. However, a thin Si absorber causes insufficient absorption of light and it should be needed to solve problems. Here, a 21-µm-thin Si photoanode for which a NiOx-coated silicon nanopyramid (SiNP) is employed is presented as a solution. The NiOx/n-SiNP structures improved the light absorption as well as the total number of catalytic sites to enable photo-oxidation reactions. A photocurrent of 7.7 mA/cm² was generated at the equilibrium potential of the OER (EOER = 1.23 V vs. a reversible hydrogen electrode in a 1 M KOH solution). Also, the photoanode did not show any degradation over the 24 hr of a photoelectrochemical water-oxidation process. [ABSTRACT FROM AUTHOR]

We present a large-scale applicable nanolens-embedding solar cell. An electrically conductive and optically transparent indium-tin-oxide (ITO) thin film was coated on a Si substrate. After then, periodically patterned ITO nanodome-arrays were formed on the ITO film by using a nano-imprint method. This structure is effective to reduce the incident light reflection for broad wavelengths and also efficient to drive the incident photons into a light-absorbing Si substrate. There exist two electric fields. One is by a p/n junction and the other is by the light absorption into Si. We designed nanolens structures to overlap two electric fields and demonstrate highly improved solar cell performances of current and voltage values from a planar structure. [ABSTRACT FROM AUTHOR]

In this study, tunneling mechanisms controlling the a-Si:H thin film/c-Si tandem solar cell were investigated employing numerical simulation. First, the effect of doped nc-Si:H tunnel recombination junction (TRJ) was studied with different structures. The band diagram, electric field, and recombination rate characteristics were investigated under a dark condition with doped nc-Si:H TRJ. The trap-assisted model and field-dependent tunneling were used to model the recombination and transport influence of the valence band offset (ΔEV) between the p-type layer of the top cell and TRJ in the high field region. Simulation results showed that the highest efficiency of 23.98% (Short circuit current density, Jsc = 18.74 mA cm−2, open circuit voltage, Voc = 1.565 V, fill factor, FF = 81.76%) could be obtained in the case of n/p nc-Si:H TRJ. [ABSTRACT FROM AUTHOR]

In this study, a cost effective and low temperature approach to fabricate a shallow-emitter crystalline silicon (c-Si) solar cell using a low sheet resistance, and highly transparent indium tin oxide (ITO) as an antireflection layer is presented. Deposited films with either (400) or (222) predominant planes were obtained by varying the substrate temperature. Better crystallization, good electrical properties, higher optical gap, and higher work function were observed for the films with (400) predominant planes; however, the transmittance in the near-infrared region suffered from free-carrier absorption effect. These ITO films were applied to replace the conventional SiNx film, as an antireflection coating for a c-Si solar cell with shallow-emitter having a sheet resistance of 100 Ω/... . Using the optimal condition, the photovoltaic parameter of the device yielded an open-circuit voltage and fill factor of up to 604 mV and 81.59%, respectively, resulting in an efficiency of 17.27%. This photovoltaic conversion efficiency, based on the c-Si solar cell with shallow-emitter, is relatively higher than that of the current reports. [ABSTRACT FROM AUTHOR]