Amorphous Silicon Solar Cells Research Articles

Sequential up-conversion and down-shifting luminescence with a tandem luminescent solar concentrator based on rare-earth and organic materials

Conventional photovoltaic systems frequently struggle to fully exploit the vast solar spectrum, falling short in efficiently converting the entire potential of each photon into electricity. This quest for maximizing solar spectrum utilization emerges as a cutting-edge research frontier within the realm of photovoltaics. In this context, we introduce a tandem luminescent solar concentrator featuring rare-earth materials (Yb3+-Er3+ doped ZBLAN) and organic dyes (Lumogen yellow and Lumogen pink) embedded within EVA polymer matrices. The incorporation of various luminescent entities plays a pivotal role in augmenting energy capture across different parts of the solar spectrum (UV, visible, and NIR). At the same time, our approach targets the synergistic integration of up-conversion and down-shifting mechanisms to achieve an optimal spectral alignment with the response profile of amorphous silicon solar cells. This involves converting UV–visible photons from incoming sunlight and visible up-converted photons from near-infrared radiation into the orange-red segment of the spectrum. Notably, this marks the initial demonstration, to the best of our knowledge, of a proof-of-concept employing a tandem luminescent solar concentrator wherein up-conversion and down-shifting photonic processes collaboratively operate in a sequential manner.

Cross-sectional profile of photocarrier mobility in thin-film solar cells via multimolecular recombination and charge extraction by linearly increasing voltage (cs-p-CELIV)

The ability to spatially resolve the carrier mobility profile along the cross section of micrometer-thin solar cells is vital, both for fundamental studies in photovoltaics and as quality control for reproducibly obtaining high conversion efficiencies in commercial solar cell modules. Presently, no technique capable of such an endeavor is available to the best of our knowledge. Here, we introduce a novel method capable of profiling the carrier mobility along the z axis in thin-film photovoltaics. Our setup is based on the integration of photogenerated charge extraction by linearly increasing voltage (p-CELIV) with a scanning confocal optical microscope (SCOM) toward a confocal and cross-sectional p-CELIV (cs-p-CELIV) system. As monomolecular recombination of excess carriers is the most frequent radiative pathway for electrons and holes in solar cells at low power density of illumination, while multimolecular recombination dominates at high power, enhanced multimolecular recombination occurs at the SCOM focal plane. Thus, the cs-p-CELIV signal provides enhanced information on the mobility of all of the cross-sectional layers except the focal plane. By scanning the focal plane along the z axis, the mobility profile can be derived. To demonstrate our technique, we use it to investigate the carrier mobility in three hydrogenated amorphous silicon (a-Si:H) solar cells. The mobility profiles obtained by cs-p-CELIV correlate well with well-known depletion layer effects and the H content profile in a-Si:H, which is measured independently. Our findings are in excellent agreement with models suggesting a critical role of Si–H bonding in locally determining the carrier mobility in a-Si:H.

Solar energy utilization with double-layer cascaded grating metamaterial

In order to produce clean energy, a double-layer cascaded grating light-trapping structure and a triangular back-reflecting Ag layer were used to improve the light-capturing ability of amorphous silicon solar cells. And the structure was compared with a planar thin-film solar cell without grating by finite element method. The average absorption of the device is improved and the tolerance of the angle is also enhanced. Besides, the physical mechanism of solar energy can be well explained by studying the electric field distribution of solar cells. The absorption of cascaded grating cells has been enhanced by 12.19%, and the average absorption efficiency at 300–800 nm is 87.91%. The performance has been significantly improved by the cascaded grating solar cells. In addition, the structure has maintained its superiority in angle analysis. This provides guidance for the preparation of wide-spectrum, wide-angle thin-film solar cells in the future.

Electronic structure of P-type amorphous silicon nanowires

Silicon nanowires can improve broadband optical absorption and reduce the radial carrier collection distance in solar cell devices. The disordered nanowire arrays grown by the Plasma-Enhanced Chemical Vapor Deposition method are attractive because they can be embedded on low-cost substrates such as glass, and are compatible with large areas. Here, we experimentally demonstrate that reactive Hydrogen ions with increasing concentrations are doped to construct nanowire architectures in amorphous silicon solar cells. Similar to our investigated planar a-Si: H layers, the amorphous silicon nanowires exhibit a loss function coefficient of about 105/cm. From the reflectivity function, it can be shown that the nanostructures can offer a reliable carrier pool. Our results show that the addition of nanowires can increase the efficiency of a-Si solar cells from 1.11% to 1.57%. The input-photon-to-current conversion efficiency spectrum shows effective carrier collection from 1.2 to 2.2 eV of incident light and the nanowire devices show an increase in short-circuit current of 15% with amorphous Si and 26% with nanocrystalline Si compared to planar devices appropriate.

Efficiency improvement in thin-film amorphous silicon solar cells based on PbS quantum dots

Efficiency improvement in thin-film amorphous silicon solar cells based on PbS quantum dots

Laser direct writing based flexible solar energy harvester

With the rapid advancement of flexible electronics, conventional rigid batteries, which serve as energy devices for flexible electronics, are no longer capable of meeting developmental requirements. In this context, solar cells, as an eco-friendly, low-carbon, and sustainable energy technology, have gained significant recognition. This paper aims to design a flexible solar energy harvester (FSEH) based on laser direct writing. The FSEH is comprised of commercial PET/PI films, flexible Cu circuits, and amorphous silicon solar cells which provide excellent flexibility and sustainability. The FSEH was formed by soldering the solar collection array to the laser direct-written flexible Cu circuit by using solder paste. The solar energy harvesting array consists of six sets of series-connected amorphous silicon solar cell arrays, with each set comprised of six amorphous silicon solar cells connected in parallel. It has a maximum light collection area of about 2772 mm2. The designed FSEH could generate energy by harvesting light energy from lights or solar radiation. The FSEH outputs 0.437 mW at the light intensity of 3000 Lux and 1.813 mW at the light intensity of 10,000 Lux. The FSEH maintains an output efficiency of over 92% with a bending angle of less than 45°. Based on laser direct writing technology which enables efficient, convenient, and large-scale production of FSEH, the FSEH is expected to form a flexible self-powered system with flexible supercapacitors and wearable electronics, and FSEH offers great advantages for the sustainable development of wearable electronics and flexible sensors.

Amorphous Silicon Thin-Film Solar Cells on Fabrics as Large-Scale Detectors for Textile Personal Protective Equipment in Active Laser Safety.

Laser safety is starting to play an increasingly important role, especially when the laser is used as a tool. Passive laser safety systems quickly reach their limits and, in some cases, provide inadequate protection. To counteract this, various active systems have been developed. Flexible and especially textile-protective materials pose a special challenge. The market still lacks personal protective equipment (PPE) for active laser safety. Covering these materials with solar cells as large-area optical detectors offers a promising possibility. In this work, an active laser protection fabric with amorphous silicon solar cells is presented as a large-scale sensor for continuous wave and pulsed lasers (down to ns). First, the fabric and the solar cells were examined separately for irradiation behavior and damage. Laser irradiation was performed at wavelengths of 245, 355, 532, and 808 nm. The solar cell sensors were then applied directly to the laser protection fabric. The damage and destruction behavior of the active laser protection system was investigated. The results show that the basic safety function of the solar cell is still preserved when the locally damaged or destroyed area is irradiated again. A simple automatic shutdown system was used to demonstrate active laser protection within 50 ms.

Integrating solar cell technologies in microalgae facilities: Environmental sustainability metrics and indicators

All solar cell technologies have an impact on the environment. So, it is important to consider that the choice of solar cell technology can have a significant influence on the environmental sustainability metrics of microalgae-based processes and products. That's why this article is concerned with scrutinizing the environmental sustainability of integrating solar cell technologies in microalgae facilities. One of the focal aspects of this research is to provide insights to stakeholders in incorporating photovoltaics into their facilities. Four solar cell technologies, namely, single-crystalline silicon, multi-crystalline silicon, copper-indium-diselenide, and amorphous silicon were investigated. The results of the study confirm that the choice of solar cell technology can further reduce the metrics of environmental sustainability indicators of microalgae-based processes and products. The energy use from the lowest emitting technology versus the highest emitting technology can lead to a reduction in sustainability metrics of 1.13 to 9.04 times. It was also revealed, from weighting the results, that integrating microalgae production with amorphous silicon solar cell technology has a lower overall environmental impact, followed sequentially by copper-indium-diselenide, multi-crystalline silicon, and monocrystalline silicon. These results provide guidance for the environmentally conscious integration of photovoltaics in microalgae facilities.

Towards a luminescent solar concentrator with ultra-broadband absorption and spectral conversion for optimizing photovoltaic solar cell response: “The photonic cannon shot”

Solar energy harvesting is largely limited by the spectral sensitivity of the employed photovoltaic solar cell, since typically the full potential of each photon of the whole solar spectrum is not efficiently used in the generation of electricity. Therefore, increasing the overall solar spectrum utilization is of crucial interest and stands up as a frontier-of-research approach in the photovoltaic sector. Here we present an innovative ultra-broadband absorption and multiple spectral conversion approach, by means of rare-earth doped materials together with organic dyes embedded in a luminescent solar concentrator. The combination of different luminescent materials is a key factor for improving energy harvesting over the whole solar spectrum. At the same time, a simultaneously combined effect of up-conversion and down-shifting of light is aimed to optimal spectral matching with amorphous silicon solar cells response. Thus, UV–visible photons coming from the incoming sunlight, together with UV–visible up-converted photons coming from near-infrared radiation, can be all shifted to the yellow-orange-red part of the spectrum. To the best of our knowledge, this represents the first reported proof-of-concept using LSCs with up-conversion and down-shifting photonic processes working together and sequentially.

Improved sustainability of solar panels by improving stability of amorphous silicon solar cells

As the world grapples with global warming, it becomes imperative to carefully examine the sustainable energy technology choices. Solar is the fastest growing clean energy source but today it contributes little to the electricity generated, so future installations will dwarf the existing installed base. There is a factor of 2–4 decrease in the energy payback time from the dominant crystalline silicon technology to thin film technologies. Essential criteria like use of abundant materials and simple but mature production technology point to amorphous silicon (a-Si) technology. Here we delve into the primary issue impeding adoption of a-Si technology—the Staebler Wronski Effect (SWE), that generates metastable, light induced defects which reduce the performance of a-Si based solar cells. We demonstrate that a simple change leads to a significant reduction in SWE power loss and define a clear path to elimination of SWE, allowing the technology to be widely adopted.

Dual metallic-based plasmonic back reflector to broaden the absorption spectra of a thin film amorphous silicon solar cell

Here, to obtain high efficiency in a thin film amorphous silicon solar cell, a dual metallic plasmonic back reflector was investigated. The designed dual metal plasmonic back reflector can improve the photocurrent and hence the efficiency. At first, a double layer SiO 2/Si3N4 as the antireflection (AR) was analyzed. The efficiencies of 8.74%, 11.38%, 12.53%, and 13.04% are obtained for a cell without AR, with SiO2, Si3N4, and SiO2/SiN 4 AR layers, respectively. A disk-ring and dual rings-based Ni and Ti-based plasmonic back reflector were designed. The study was carried out by a 3D finite difference time domain method and the optimized parameters were calculated to obtain higher efficiencies. Finally, a relatively higher photocurrent and conversion efficiency of 19.86mA/cm2 and 15.65% were achieved for the optimized structure with a dual Ni rings back reflector, respectively. Because of the importance of amorphous silicon solar cells due to the cost problem of crystalline silicon, here, the simulation steps present a valuable road map to design a novel plasmonic thin-film amorphous silicon solar cell.

Optical modelling of TCO based FTO/TiO2 multilayer thin films and simulation in hydrogenated amorphous silicon solar cell

Hydrogenated Amorphous silicon (a:Si:H) has low amounts of defects making it attractive for photovoltaic applications. To improve power conversion efficiency (PCE) of a:Si:H solar cells, this study investigated the effect of introducing FTO/TiO2 multilayer thin films into its structure to serve as antireflection coating. The multilayer thin films were characterized and optimized by optical simulations using a computer program, GLSIM (glazing simulator). The program was written in FORTRAN and implemented in MATLAB. The multi-Fresnel equations were employed to create the GLSIM program. Then using the program, together with the pairs of real and imaginary values of complex refractive index, n and k respectively, the transmittance and reflectance data of FTO/TiO2 multilayer thin films on glass substrate were computed. The optimized FTO/TiO2 multilayer thin films were then incorporated into silicon solar cell with structure glass/FTO/TiO2/n-a-Si:H/i-a-Si:H/p-a:Si:H/P+-BSF and characterized using SCAPS-1D software. The effect of varying layer thickness on the solar cell performance was also investigated. The optimized solar cell had a thickness of 100 nm, 50 nm, 900 nm, 100 nm, 10μm and 5μm for FTO, TiO2, n-a-Si:H, i-a-Si:H, p-a-Si:H and P+-BSF respectively. The device output performance were 37.96 mA/cm2, 1.34 V, 56.37% and 28.72% for Jsc, Voc, FF and η respectively showing a remarkable improvement in the solar cell performance. These results show potential of fabricating an improved hydrogenated silicon solar cell.

Computational modelling of light-matter interaction in aSi with CdSe/ZnS core/shell quantum dots and metal nanoantenna for solar cell applications

As the world population rises, energy needs are become critical. Using photovoltaic technologies like amorphous silicon solar cells (aSiSC) to harvest solar power might benefit global concern. Previous research claimed that aSiSCs were modest short-wavelength absorbers. Quantum dot (QD) may be applied to the aSiSC to enhance optical absorptions and electric fields as the QD’s bandgap is tunable, which can cover a broader electromagnetic range. This study aims are to design the 3D aSiSC with QD on the model and to investigate the optical absorption peak, electric field profiles, and light–matter interaction of the models via COMSOL Multiphysics software. From the base model, the optical absorption improved from 736 nm at 41.827% to 46.005% at 642 nm for the aSiQDSC model which developed with 0.5/3.0 nm radius of core/shell cadmium selenide/zinc sulphide (CdSe/ZnS). This study proceeded combining rectangular nanosheets gold and silver nanoantenna (Au and Ag NA) with various gap g of NA to the aSiQDSC models where g = 0.5 nm Ag NA model was presented the higher optical absorption of 47.246% at 650 nm, and electric fields of 2.53 × 1010 V nm−1. Computationally, this ultimate design is ecologically sound for solar cell applications, which allow future direction in renewable energy research and fabrication.

P‐9.2: ESL products with amorphous silicon solar cells integrated into the backplane

This paper presents a product combining amorphous silicon solar cells and ESL. This product combines the amorphous silicon solar cell process with the TFT backplane of ESL products. At the same time, this product uses solar cells as the device for collecting light energy, and the new energy conversion equipment collects the electric energy generated by solar energy and generates stable output electric energy to provide ESL devices. This scheme is not only environmentally friendly, but also reduces the thickness of products using external solar cells.

Optimization of distributed Bragg’s reflectors in thin film solar cells

Distributed Bragg reflectors (DBRs) or one-dimensional photonic crystals (1DPCs) play key role in advanced opto-electronic and photonic devices. The term photonics is derived from photons in which particle indicates a quantum of light and photon carries energy proportional to the radiation frequency with zero rest mass. In this work, we present the designing 1DPCs by using Si/SiO2 layers using a plane wave expansion method (PWE). For that, various parameters are optimized such as thicknesses (d) of each layer, center wavelength (λc), refractive index (nH/nL) of individual layer and the number of DBR/period to analyze the photonic band gap (PBG). The transverse electric (TE) and magnetic (TM) field distribution at different wavelength is discussed and helpful to understand the light harvesting mechanism within the PBG. Finally, this optimized DBR layers were integrated into a thin film amorphous silicon solar cell as a back-end reflector. Due to the tuned PBG, the proposed and designed amorphous silicon thin film solar cell has yielded an improved of light absorption, which is useful for enhancing the photovoltaic performance.

A simulation approach for optimization of optical absorption in amorphous silicon solar cell

One of the major drawbacks of thin-film silicon solar cells is their limited optical absorptance due to the thin absorber layer and the minimal absorption coefficient. The mechanism of using surface textured interface in layered structure is widely accepted to scatter light and enhance the optical path length, which in turn enhances the optical absorption and improves the solar cell efficiency. A textured amorphous silicon solar cell is designed in order to observe the impact of scattering layers on optical absorption and efficiency. A pyramid, cylindrical and micro lenses array structure has been simulated using simulation tool used to obtain the optimum absorption at a particular wave length. A max Power conversion efficiency of 0.0992 is obtained at Voc of 0.9218 V. In this regard, the impact of scattering layers and different geometrical structure on V-I characteristics solar cell were observed. The maximum value obtained for refractive index is 2.0 for optimized a-Si solar cell.

Towards the limitation of optical absorption dissipations of amorphous silicon solar cells based on annular concave anti-reflecting coating

We present in this research study an investigation towards the limitation of absorption reduction through Si solar cells with the variation of the angle of incidence. Our study is essentially based on the design of an anti-reflecting coating from a single period of one-dimensional quadrant photonic crystals (PCs) with concave and convex curvatures. Moreover, the effect of the one-dimensional PCs as a back mirror on the absorption of the cell was investigated. The numerical findings show that the solar cell absorption is significantly affected by the change in the angle of incidence. For concave an anti-reflecting coating, as the radius of curvature decreases to 50 nm, the solar cell absorption investigates significant enhancements with the angle of incidence. Considering planar and concave geometries is more preferred than the convex one whatever the radius of curvature of the constituent layers. The presence of an anti-reflecting coating with a small value of the radius of curvature is the most compatible design for silicon solar cells for capturing most of the incident photons on the cell and improving the cell absorption as well.

Optoelectronic refractometric sensing device for gases based on dielectric bow-ties and amorphous silicon solar cells

The transformation of an hydrogenated amorphous silicon solar cell (aSiH) into an optoelectronic refratometric sensor has been possible through the addition of dielectric bow-tie resonant structures. The indium transparent oxide top electrode is replaced by a thin metallic layer to selectively prevent the direct transmission of light to the active layer of the cell. Then, an array of dielectric bow-tie structures is placed on top of this electrode, to activate the optical absorption through surface plasmon resonance (SPR). The whole device is exposed to the analyte under measure, which is the surrounding medium. Three different dielectric materials with low, medium, and high refractive index were selected for the bow-ties, namely magnesium fluoride (MgF_2), silicon dioxide (SiO_2), and aluminum nitride (AlN) have been tested as coupling structure for SPR excitation. The maximization of the readout/short circuit current has been achieved through the geometrical parameters of such structure. We have selected the geometrical parameters to maximize the short circuit current delivered by the a-Si cell at a given selected wavelength. The design has been customized to gas measurements application, where the index of refraction is slightly above 1 around 10^{-4}. Our analysis reveals ultra-high sensitivity of 2.4 times 10^4 (mA/W)/RIU, and a figure of merit FOM= 107 RIU^{-1}, when the bow-tie is made of SiO_2. A performance rally competitive with those previously reported in literature, with the additional advantage of circunventing both moving parts and spectral interrogation elements.

Highly transmitted silver nanowires-SWCNTs conductive flexible film by nested density structure and aluminum-doped zinc oxide capping layer for flexible amorphous silicon solar cells

• Ag NWs-SWCNTs (AS) composites with high and sparse density networks were fabricated by ultrasonic. • The AS/AZO (ASA) bilayer showed superior transmittance (92%@550 nm), mechanicity, stability, and adhesion. • The film demonstrates high stability with a ΔR/R 0 = 10% after 10,000 bending times, boiling, taping, and CO 2 plasma. • The power conversion efficiency of photovoltaic devices with flexible ASA TCFs was increased by 26%. • No significant reduction in power conversion efficiency was observed even after bending for 3000 times. Indium tin oxide (ITO) is widely used in transparent conductive films (TCFs); however, several disadvantages, such as high cost and toxicity of indium, limit its applications. Therefore, it is necessary to develop other materials that can replace ITO. Silver nanowires or single walled carbon nanotubes (SWCNTs) have attracted considerable interest owing to their unique electrical, optical, and thermal stabilities, and thus, they are ideal for transparent electrodes for flexible or stretchable devices. In this study, we develop a novel architecture of composite TCFs on a polyethylene naphthalate (PEN) flexible substrate. Herein, the silver nanowires-SWCNTs films with nested density structure were fabricated through ultrasonic spraying technology by varying the spraying width. For achieving enhanced transmittance, we combined the larger irregular grids and holes with fewer nanowires stacked in the longitudinal direction, more optical channels, and good carrier transport. Thereafter, aluminum-doped zinc oxide (AZO) was used as capping to the structure for enhancing the optical properties of the TCFs. The silver nanowires-SWCNTs/AZO (ASA) bilayer was obtained in the optimized architecture, which showed superior optoelectronic performance to that shown by commercial ITO with a high optical transmittance of 92% at the wavelength of 550 nm and low sheet resistance of 17 Ω/sq. In the specially structured conductive film, the significant improvement in the transmittance and uniformity of the sheet resistance was attributed to the effective nanowire junction contact compared to that in ordinary structure of silver nanowires, which reduced the mean density of small clusters of nanowires. Compared with the silver nanowires-SWCNTs films, the ASA bilayer film exhibited excellent resistance to boiling, mechanical bending (10,000 cycles), and CO 2 plasma. Moreover, the sheet resistance of ASA changed slightly after the tape tests, thereby illustrating a strong adhesion to the PEN substrate after the enclosure of AZO. Meanwhile, the AZO capping layer can enhance the optical transmittance between 600 and 1500 nm. In addition, the amorphous silicon photovoltaic devices with flexible ASA TCFs exhibited a power conversion efficiency (PCE) of 8.67%. After bending for 3000 times, the PCE was decreased to 8.20%, thereby demonstrating the potential of developed films to replace traditional ITO.

Theoretical Analysis of Optical Properties for Amorphous Silicon Solar Cells with Adding Anti-Reflective Coating Photonic Crystals

In the current study, we aim to limit the power dissipation in amorphous silicon solar cells by enhancing the cell absorbance at different incident angles. The current improvement is justified by adding the single-period of ternary 1D photonic crystal with texturing on the top surface, which acts as an anti-reflecting coating. The texturing shape gives the photons at least two chances to localize inside the active area of the cell. Therefore, it increases the absorbance of the cell. Moreover, we add binary one-dimensional photonic crystals with the features of a photonic band gap, which acts as a back mirror to return the photons that were transmitted inside the cell’s active region. The considered structure is demonstrated by the well-defined finite element method (FEM) by using COMSOL multiphysics.