Easily Prepared Transparent Electrodes for Low-Cost Semitransparent Inverted Polymer Solar Cells

The continuous thin film of silver (Ag) film is important for semitransparent electrodes in polymer solar cells, while the Ag atoms form as non-continuous below a critical thickness. Here, semitransparent inverted polymer solar cells were fabricated using thermally evaporated Ag/germanium (Ge)/Ag as highly transparent electrodes. An ultra-thin Ge film was introduced to modify the growth mode of Ag. The dependence of the device performance and the thickness of the outer Ag film was investigated. Ag/Ge/Ag electrodes exhibited excellent optical and electrical properties, which were proved by the transmittance and reflectance spectra. A champion efficiency of 5.1% was achieved with an open-circuit voltage level of 0.703 V, a short current density of 11.63 mA/cm2, and a fill factor of 63%. The average visible transmittance (300–800 nm) of devices with Ag/Ge/Ag was calculated as 25%.

Квантовый выход двусторонних солнечных элементов типа HIT

In this paper we showed that illumination of both front and back sides of heterojunction solar cells contribute efficiency. The obtained spectral dispersion of quantum efficiency confirms that contribution depends on conversion of short-wave photonts. The average difference between quantum efficiency of both sides is ∼ 11%. Under standard solar illumination in the 400−1100 nm wavelength range the short-current density for front side is 36.3 mA/cm² and 32.7 mA/cm² for back side with reduction about 10%.

Electrochemical Epitaxial Growth of TiO2/CdS/PbS Nanocables

Electrochemical deposition as a liquid phase epitaxial growth method is widely used to fabricate different kinds of hierarchical structures. As a typical heterostructure, TiO2/PbS is widely utilized in the areas of photovoltaics and photocatalysis. Oriented TiO2 nanorod (NR) arrays can provide direct pathways for the electron transport of photoanode. However, the lattice mismatch between TiO2 NR sides and PbS is very large; PbS nanoparticles (NPs) only formed on the top of TiO2 NRs. To solve this problem, TiO2/CdS core/shell nanocables were firstly prepared electrochemically because the lattice ratio between TiO2 and CdS was 0.916; and then, PbS NPs were successfully deposited over CdS shells (the lattice ratio between CdS and PbS was 0.697) to form TiO2/CdS/PbS hierarchical heterostructures. Experimental results demonstrated that the CdS interlayer could effectively promote the growth of PbS NPs on the surface and improve the fill factor and short current density of the photoanodes.

UNDERSTANDING THE EFFECT OF DEPRESSOR ON THE TIO2 COMPACT LAYER FOR THE PHOTOCURRENT PERFORMANCE OF PEROVSKITE SOLAR CELLS

The main purpose of a compact TiO2 film as a vital part of the electron transport layer in perovskite solar cells (PSCs) is to minimize electron–hole recombination on the surface of F-doped SnO2 (FTO) and enhance the photoelectric property. By controlling concentrations and using different depressors, an excellent compact TiO2 film is prepared by sol–gel method. This research utilized four depressors (nitric acid, acetic acid, diethanolamine and acetylacetone) and their volume ratios to ethanol are 0, 1:1 and 1:2 to synthesize the TiO2 precursor sol. The surface morphology, ingredient and microstructure as well as the optical and electrochemical properties of PSC devices based on them are investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV–visible absorption spectroscopy (UV–Vis), respectively. It is found that the device exhibited the most outstanding power conversion efficiency (PCE) of 14.92% via using diethanolamine as the depressor diluted in absolute ethanol in a proportion of 1:1 by volume. Further study showed that the enhanced PCE could be mainly ascribed to the increase of short-current density ([Formula: see text].

Simulation of n-β-FeSi2/p-Si heterojunction solar cells based on AFORS-HET

Semiconducting thin [Formula: see text]-FeSi2 film has been recognized as a novel solar cell material due to its high absorption coefficient. In this study, the effects of emitter on the photovoltaic properties of n-[Formula: see text]-FeSi2/p-Si were analyzed using AFORS-HET program. The simulation results show that the thickness of emitter affects the conversion efficiency of solar cell, and the short-current density decreases sharply with increasing thickness of emitter. Interface state is another key factor influencing the conversion efficiency of solar cell, which degrades solar cell performance. In order to obtain high efficiency battery, interface state density should be less than 10[Formula: see text] cm[Formula: see text] eV.

Ultra-thin LiF Layer As The Electron Collector For a-Si:H Based Photovoltaic Cell

ABSTRACTAn ultra-thin LiF layer in conjunction with an Al layer is employed as the electron collector for the a-Si:H based single-junction thin film photovoltaic cell. The cell has the structure of boron doped μ-SiOx (hole collector) - intrinsic a-Si:H (photoactive layer) - LiF / Al (electron collector and back electrode). The substrate used is U type Asahi glass, which is also acting as the transparent front electrode. For the cell with the 1.5 nm thick LiF layer, annealed at 120°C, the open current voltage (VOC) of 0.936 V, the short current density (JSC) of 13.598 mA/cm2, and the fill factor (FF) of 0.690 are achieved. The JSC and VOC values are comparable to the values measured for the a-Si:H based p-i-n reference cell, but the FF value is found to be lower, which is attributed to the losses due to recombination at the intrinsic a-Si:H / LiF / Al junction. The current versus voltage measurements are carried out under the standard test conditions. The JSC values are corrected according to the external quantum efficiency measurements of the cells in the AM1.5 spectrum region between 270 nm and 800 nm.

MoOx Hole Collection Layer for a-Si:H Based Photovoltaic Cells

ABSTRACTAn experimental investigation to verify the suitability of MoOx as the hole collection layer for a-Si:H based thin film photovoltaic cell is carried out. The photovoltaic cell investigated has the structure of MoOx (hole collection layer) / intrinsic a-Si:H (photoactive layer) / phosphorus doped a-Si:H (electron collection layer) / Ag (back reflector electrode); all deposited in that order onto an Asahi glass (type U) substrate, which is also acting as the transparent front electrode for the cell. The effects of different post deposition annealing temperatures are investigated. The highest efficiency values are obtained for the cells annealed at 120°C. For the photovoltaic cell with 100 nm thick photoactive layer, the highest efficiency is measured to be 6.46 % with an open current voltage (Voc) of 827 mV and a short current density of (Jsc) of 10.44 mA/cm2. For the photovoltaic cell with 300 nm thick photoactive layer, the highest efficiency is measured to be 7.93 % with Voc of 818 mV and Jsc of 13.24 mA/cm2. The efficiency measurements are carried out under AM1.5 test conditions. Jsc values are corrected according to the external quantum efficiency measurements of the cells in the AM1.5 photovoltaic spectrum region between 270 nm and 800 nm. Compared to the reference cell with boron doped μ-SiOx layer acting as the hole collection layer, the cell with MoOx hole collection layer has similar FF, lower Voc, higher Jsc for wavelength up to the green light region of the AM1.5 spectrum and lower Jsc for the longer wavelengths.

Characterization of PbS thin films obtained by chemical bath at low temperature using sodium citrate as complexing agent

ABSTRACTThe deposition of PbS thin films by the chemical bath deposition method using sodium citrate as non-toxic complexing agent is presented. As-deposited PbS films and those annealed at 200 and 300 °C in argon atmosphere were formed by tightly compact spherical particles homogeneously distributed along the substrates. The XRD analysis shows that all the films had a galena type cubic crystalline structure. The crystallite size of the as-deposited film was 17 nm which decreased to 14 nm when the film was annealed to 300 °C. Thermal treatments to the films produced a shift of the optical band gap from 1.34 to 1.49 eV. Furthermore, the as-deposited PbS films were photosensitive showing a conductivity of 10-2 Ω-1 cm-1 under illumination. Such a conductivity increased to 10-1 Ω-1 cm-1 with the thermal treatment at 200 °C. The evaluation of the PbS film using a CdS thin film partner as window in the solar cell configuration showed an open circuit voltage of 88 mV and a short current density of 3.5 mA/cm2.

Periodic Nanostructured Thin-Film Solar Cells

Si-based photonic crystal device such as solar cells have been developed and attract lots of attention. Whether what kind of different structures are used, two key problems are needed to investigate. One is the improvement of the optic-electric (or electric-optic) transformation efficiency. Another is the capability to modulate the light-emitting and detection wavelength for various industrial applications. The wavelength of the light emission and detection can also be further adjusted by changing the material band-gap. In this work, we develop the periodic nanoscale surface textured solar cells. The characteristics of top thin film textured solar cells is developed and estimated to see if the structure is worthy to be scaled from the modern micrometer (um) level down to the nanometer (nm) level continuously. The process of nm-scale textured Si optoelectronic device used in this work is fully comparable to the modern CMOS industry. Optimal Ge concentration in SiGe-based solar cells has been investigated qualitatively by the systemic experiments. With the appropriate addition of Ge to a SiGe-based solar cell, the short current density (Isc) is successfully increased without affecting the open-circuit voltage (Voc) and then the overall efficiency is successfully improved about 4 % than the nanoscale surface textured Si solar cell.