Recent advances and new research trends in Sb2S3 thin film based solar cells

Although many environmentally friendly and non-toxic materials have been investigated for photovoltaic conversion (PVC) applications, Sb2S3 is the material of choice as an absorber in thin-film solar cells due to its broad-band optical response and excellent electrical properties. Though an Sb2S3 thin-film was predicted to have a 28% efficiency, the reported efficiency of 7% is significantly lower than the theoretically predicted efficiency and less competitive compared to other similar thin-film solar cells. This review investigates how structural and morphological changes in Sb2S3 thin films contribute to the current state of Sb2S3 solar cell development to understand and improve current device performance. We first discuss the fundamental structure and properties of Sb2S3 and then show how morphology and structural changes in Sb2S3 thin films produced using various fabrication techniques and conditions affect solar cell performance. This research includes several significant recent developments and current research trends that will pave the way for future improvements in the performance of Sb2S3-based photovoltaic solar cells

Optimization and tuning of the aspect ratio of hydrothermally grown ZnO nanorods by varying the hydrothermal temperature and their electron transport properties

In this investigation, a facile method to synthesize 1-D ZnO nanorod having different aspect ratio by varying the hydrothermal temperature was demonstrated. The hydrothermal reaction temperatures were optimized to obtain high aspect ratio ZnO nanorods with well-defined 1-D structures. The aspect ratio depended electron transport properties, charge recombination, chemical capacitance, life-time and charge diffusion length of 1-D ZnO nanostructures were investigated. It was observed a clear correlation between the aspect ratio and the electron transport properties of ZnO nanorods. The highest aspect ratio of 7.6 was obtained for the ZnO nanorods synthesized at 100–120 °C and was found to have the highest electron transport properties. It was demonstrated the formation of highly crystalline, high-aspect ratio 1-D ZnO nanorods with enhanced electron transport properties at low hydrothermal temperatures which will be beneficial for device applications

Piezoelectric materials for catalytic/photocatalytic removal of pollutants: Recent advances and outlook

The accumulation of various contaminants in air, soil and water is threatening the natural environment. The remediation of the environmental contaminations is today an urge. Among the remediation methods employed, advanced oxidation processes (AOPs) are a class of techniques based on the in situ generation of highly reactive and oxidizing radical species which can destroy most of the organic pollutants. AOPs driven by light are found to be the most popular for wastewater treatment due to the abundance of solar light in some regions. The removal of organic contaminants using semiconductor-based photocatalysts has been extensively investigated. However, low charge carrier mobility and rapid electron-hole pair recombination are the common problems that limit the semiconductor-based photocatalysis. Although a large number of alternative systems have been investigated, electron-hole pair separation is still too low in photocatalytic systems. A new concept was introduced recently in which the built-in electric field by ferroelectric, pyroelectric and piezoelectric effects in photocatalytic particles was exploited to enhance the separation of photoinduced charge carriers. Among these new systems that are still under investigation, the use of piezoelectric materials in the photodegradation of pollutants recently drew a lot of attention for environmental remediation. Due to the non-centrosymmetric nature, the piezoelectric materials demonstrate unique catalytic properties as a result of the creation of the built-in electric field by the dipole polarization. This latter provides a driving force for the transport of the photoinduced charge carriers enabling their separation. This review covers the use of piezoelectric materials in photocatalysis and catalysis, especially piezoelectric-catalysis, for environmental remediation. The paper details the fundamentals and basic properties of ferroelectric, pyroelectric and piezoelectric materials. The effect of the built-in electric field in these materials on the photocatalysis/catalysis charge carrier separation is discussed. Possible applications of piezoelectric materials in environmental remediation are reviewed and discussed taking into account several different aspects such as the kinetics of the degradation of the organic pollutants and water splitting. Finally, the current research trends and future prospects of piezocatalysis and piezophotocatalysis are discussed

Significant role of the initial precursor sulfur concentration in the photoelectrochemical hydrogen production of Cu2ZnSnS4 photocathode prepared by thermal evaporation

The thermal evaporation of Cu2ZnSnS4 (CZTS) nanoparticles synthesized by changing the sulfur ratio in the precursor solution was used to investigate the critical role of sulfur concentration in the photoelectrochemical (PEC) water splitting reactions of the CZTS photocathode. X-ray diffraction, transmission electron microscopy, UV-visible spectroscopy, impedance spectroscopy, capacity measurement, and PEC performance measurement were used to investigate the effect of precursor sulfur concentration on the structural, morphological, optical, and PEC performance of films. The half-cell solar-to-hydrogen efficiency of CZTS photoelectrodes increased as the sulfur content increased. The power conversion efficiency of the CZTS cathode constructed with CZTS nanoparticles synthesized with a 0.8 to 1.0 M precursor sulfur concentration was 0.32% at 0 V versus RHE under AM 1.5 illumination. The increase in crystallite size and charge carrier concentration is observed with increasing precursor sulfur concentration, and the maximum crystallite size and charge carrier concentration are observed at 1.0 M sulfur concentration. By carefully adjusting the crystallite size and thus the charge carrier concentration of the CZTS material, the PEC water splitting efficiency of the CZTS photocathode can be improved. (C) 2022 Society of Photo-Optical Instrumentation Engineers (SPIE

Sono-photocatalytic production of hydrogen by interface modified metal oxide insulators

Dielectric oxide materials are well-known insulators that have many applications in catalysis as well as in device manufacturing industries. However, these dielectric materials cannot be employed directly in photochemical reactions that are initiated by the absorption of UV-Vis photons. Despite their insensitivity to solar energy, dielectric materials can be made sono-photoactive even for low energy IR photons by modifications of the interfacial properties of dielectric materials by noble metals and metal oxides. In this investigation, by way of interface modification of dielectric MgO nanoparticles by Ag metal and Ag2O nanoparticles, IR photon initiated sono-photocatalytic activity of MgO is reported. The observed photocatalytic activity is found to be the synergic action of both IR light and sonication effect and sonication assisted a multi-step, sub-bandgap excitation of electrons in the MgO is proposed for the observed catalytic activity of Ag/Ag2O coated MgO nanoparticles. Our investigation reveals that other dielectric materials such as silver coated SiO2 and Al2O3 also exhibit IR active sono-photocatalytic activity

Efficiency enhancement by mixed cation effect in dye-sensitized solar cells with PAN based gel polymer electrolyte

Dye-sensitized solar cells based on nano-porous TiO2 photo-anode and quasi-solid polymer (or gel) electrolytes are emerging as low cost alternatives to conventional inorganic photovoltaic devices. Although many attempts have been made in order to improve the relatively low power conversion efficiencies of these solar cells, to our knowledge there are very few reports aimed at using a binary system of two different iodide salts toward efficiency enhancement in these cells. In this paper we report for the first time in detail, the effect of using a binary iodide salt mixture with different size cations on the efficiency enhancement in dye sensitized solar cells with polyacrylonitrile (PAN) based gel polymer electrolyte and suggest a possible mechanism for this enhancement, based on short circuit photocurrent which is directly related to the iodide ion concentration [I-]. The gel electrolyte was made of PAN, ethelene carbonate (EC), Propylene carbonate (PC), salt mixture and I-2. The binary iodide salt mixture consists of potassium iodide (KI) and Tetra propyl ammonium iodide (Pr4NI). Although the gel electrolyte with 100% (w/w) KI exhibited the highest overall ionic conductivity at room temperature, it showed the lowest iodide ion (I-) contribution to conductivity. On the other hand, the electrolyte with 100% (w/w) Pr4NI exhibited the lowest overall ionic conductivity but had the highest iodide ion(I-) contribution. The dye-sensitized solar cells of configuration Glass/FTO/TiO2/N-719 Dye/electrolyte/Pt/FTO/glass were fabricated using the gel electrolytes of different salt ratios and with nanoporous TiO2 electrode sensitized with Ruthenium dye (N719). With identical electrolyte compositions, the solar cell with 100% (w/w) KI showed an efficiency of 4.98% and the cell with 100% (w/w) Pr4NI showed an efficiency of 4.47%. However, the cell with the mixed iodide system, 16.6% (w/w) KI + 83.4%(w/w) Pr4NI showed the highest efficiency of 5.36% with maximum short circuit current density (J(SC)) of 13.79 mA cm(-2), open circuit voltage (V-OC) of 679.10 mV and a fill factor of 57.25%. The variation of efficiency (eta) with iodide ion concentration [I-] follows the same trend as the J(SC) which appears to be governed by the iodide ion conductivity of the gel electrolyte. The dependence of the short circuit photocurrent and the open circuit photovoltage on the cation type generally agrees with reported data for related systems. However, the occurrence of a maximum in the solar cell efficiency and short circuit photocurrent at 16.6% (w/w)10 + 83.4% (w/w) Pr4NI salt composition is an important finding. The efficiency enhancement of about 8% achieved by employing the binary iodide mixture in the gel electrolyte instead of a single iodide salt, could be utilized for achieving efficiency enhancement in many dye sensitized solar cell systems based on polymeric, gel or solvent electrolytes