We review the technical progress made in the past several years in the area of mono- and polycrystalline thin-film photovoltaic (PV) technologies based on Si, III–V, II–VI, and I–III–VI
2 ...semiconductors, as well as nano-PV. PV electricity is one of the best options for sustainable future energy requirements of the world. At present, the PV market is growing rapidly at an annual rate of 35–40%, with PV production around 10.66
GW in 2009. Si and GaAs monocrystalline solar cell efficiencies are very close to the theoretically predicted maximum values. Mono- and polycrystalline wafer Si solar cells remain the predominant PV technology with module production cost around $1.50 per peak watt. Thin-film PV was developed as a means of substantially reducing the cost of solar cells. Remarkable progress has been achieved in this field in recent years. CdTe and Cu(In,Ga)Se
2 thin-film solar cells demonstrated record efficiencies of 16.5% and almost 20%, respectively. These values are the highest achieved for thin-film solar cells. Production cost of CdTe thin-film modules is presently around $0.76 per peak watt.
Dye-sensitised solar cell (DSSC) technology has seen some radical advancement recently owing to the new materials and device structure innovations. The efficiency increase in the solid state version ...of DSSCs from about 5% to over 15% have been reported within two years of time scale, which comes mainly from the efforts in the perovskites based mesoporous solar cells developments. This has increased its potential significantly to become a low cost alternative for commercially available solar cell technologies. The progress of the liquid junction based DSSCs towards their better performance and stability had been relatively slower and was coupled with scale up and engineering challenges such as encapsulation, sealing of the device, etc. The efficiency figures for conventional DSSCs had been staying stagnant for almost two decades although many research groups had been concentrating to improve the efficiency of DSSC through various ways. The recent developments on the solid state DSSCs have given a solid belief for this technology to make a mark towards its commercialisation. Although a great progress in the device efficiency has been made but a lot of efforts are still needed to break the barriers which had been preventing this from penetrating the market. An attempt has been made through this article to report the recent developments in the liquid junction, quasi and solid state versions of the DSSC technology with their state of the art efficiency figures reflecting their current status.
•Current status of the liquid, quasi and solid state electrolytes based dye sensitised solar cells•State-of-the-art efficiency figures for various types of dye sensitised solar cells•Recent developments on the solid state perovskites based mesoporous solar cells
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•Tin selenide was synthesized by solid state reaction.•Screen printing method has been adopted to prepare SnSe films to act as CE in DSSCs.•The DSSC fabricated with SnSe CE exhibited ...good photocatalytic behaviour and photo conversion parameters.•Further modification in the SnSe CE preparation can lead to be an efficient and alternative to Pt.
In this work, the scalable screen printing process has been adopted to prepare low-cost and earth-abundant tin selenide (SnSe) films to study as the counter electrode in dye-sensitized solar cells (DSSCs). The SnSe powder was synthesized by solid state reaction method and corresponding films were fabricated by screen printing technique. The electrocatalytic activity of SnSe for redox iodide/triiodide (I−/I3−) couple and charge transfer resistance at the CE/electrolyte interface were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The DSSC with SnSe counter electrode exhibited with power conversion efficiency (PCE) of ~5.76% with open-circuit voltage of 0.63 V and short circuit current density of 12.39 mA/cm2 whereas the DSSC with platinum counter electrode showed PCE of 8.09% with open-circuit voltage of 0.68 V and short circuit current density of 14.77 mA/cm2. Thus, earth abundant and low cost SnSe films fabricated by screen printing technique could be an alternative to costly platinum counter electrode in DSSC.
The proposed surface-mountable self-isolated MIMO antenna covers n78 and n79 5G frequency bands. The presented design has two semicircular slots with engineered geometry to get the desired frequency ...spectrum. Antenna presents the bandwidth in the order of 8.77% and 2.81% at frequency resonance of 3.42 GHz and 4.98 GHz, respectively, covering FR1 5G and WLAN applications. The design presents an acceptable gain of 2.95 dBi and 2.42 dBi. The elements of MIMO antennas are kept an adequate distance apart to achieve self-isolation in order of 19 dB. It aids further in achieving optimal MIMO diversity parameters. The 2D electrical size of the presented self-isolated planar antenna is 0.97λ × 0.65λ at the lowest resonance. The MIMO antenna parameters were examined for the stated antenna design. The optimal envelope correlation coefficient (ECC) is near to 0.02, channel capacity loss (CCL) is around 0.2 bits/sec/Hz, directivity gain (DG) is around 9.98 dB, and the MEG ratios are near to unity. The computed performance of the resonator is validated through fabrication and experimentally tested using VNA 9912A in an anechoic chamber environment.
CdTe films with different compositions (Cd-rich, Te-rich and stoichiometric) were fabricated by a novel and low cost chemical molecular beam deposition method (CMBD) in atmospheric pressure hydrogen ...flow. Cd and Te granules were used as precursors. The films were deposited on ceramic (SiO
2:Al
2O
3) substrates at 580
°C and 600
°C. The growth rate was varied in the range of 9–30
Å/s. The composition (Cd/Te) of the samples was changed by controlling the molecular beam intensity (MBI) ratio. Three samples fabricated at MBI ratios Cd/Te
=
0.5, 1.0 and 1.16 were investigated by XRD, AFM, EDX, SEM, photoluminescence (PL) and Hall methods.
Chickpea is considered sensitive to salinity, but the salinity resistance of chickpea germplasm has rarely been explored. This study aimed to (i) determine whether there is consistent genetic ...variation for salinity resistance in the chickpea minicore and reference collections; (ii) determine whether the range of salinity resistance is similar across two of the key soil types on which chickpea is grown; (iii) assess the strength of the relationship between the yield under saline conditions and that under non‐saline conditions; and (iv) test whether salinity resistance is related to differences in seed set under saline conditions across soils and seasons. The seed yield of 265 chickpea genotypes in 2005–2006 and 294 cultivated genotypes of the reference set in 2007–2008 were measured. This included 211 accessions of the minicore collection of chickpea germplasm from the International Crops Research Institute for the Semi‐Arid Tropics (ICRISAT). The experiments were conducted in a partly controlled environment using a Vertisol soil in 2005–2006 and an Alfisol soil in 2007–2008, with or without 80 mm sodium chloride (NaCl) added prior to planting. In a separate experiment in 2006–2007, 108 genotypes (common across 2005–2006 and 2007–2008 evaluations) were grown under saline (80 mm NaCl) and non‐saline conditions in a Vertisol and an Alfisol soil. In 2005–2006 in the Vertisol and 2007–2008 in the Alfisol, salinity delayed flowering and maturity, and reduced both shoot biomass and seed yield at maturity. There was a large variation in seed yield among the genotypes in the saline pots, and a small genotype by environment interaction for grain yield in both soil types. The non‐saline control yields explained only 12–15 % of the variation of the saline yields indicating that evaluation for salinity resistance needs to be conducted under saline conditions. The reduction in yield in the saline soil compared with the non‐saline soil was more severe in the Alfisol than in the Vertisol, but rank order was similar in both soil types with a few exceptions. Yield reductions due to salinity were closely associated with fewer pods and seeds per pot (61–91 %) and to lesser extent from less plant biomass (12–27 %), but not seed size. Groups of consistently salinity resistant genotypes and the ones specifically resistant in Vertisols were identified for use as donor sources for crossing with existing chickpea cultivars.
Dye sensitized solar cells (DSCs) have the potential to be used as a top device in a tandem solar cell structure with a bottom Cu(In,Ga)Se
2 (CIGS) cell. Optical losses, however, within the fluorine ...doped tin oxide (FTO) conducting electrode used with DSCs limit the light available for the bottom cell for photocurrent generation, and therefore the whole device. High mobility transparent conducting oxides have the potential to reduce these optical losses, since the transmission in the near infrared of these substrates is high compared to standard conducting oxides. Attempts have in the past been made to use these conducting oxide substrates as the electrodes in DSCs; however delamination of the deposited TiO
2 layer and an increase in sheet resistance of the high mobility material have caused problems. Here we present alternative surface treatments to ensure that delamination is significantly reduced, as well as a method to recover lost conductivity of heated indium oxide films, which result in transparent cells of over 7% efficiency, which is close to that reached on standard FTO substrates.
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