Thin-film Photovoltaic Technologies Research Articles

Seasonal performance estimation of thin film photovoltaic technology

The performance of photovoltaic (PV) module in the environment can be improved by considering the seasonal effects. In this paper, the effect of seasonal variations of Amorphous-Silicon/thin film photovoltaic technology in different seasons has been presented for National Institute of Solar Energy (NISE), Gurgaon site in India. It has been observed that, the estimation efficiency and output power of a-Si technology using module temperature is well match to measured efficiency and output power. This study is mainly very important in India because of the each season’s variation effect on different PV technology will be useful for large scale project assessment.

A Unified Approach for Analysis of Faults in Different Configurations of PV Arrays and Its Impact on Power Grid

Fault analysis in photovoltaic (PV) arrays is considered important for improving the safety and efficiency of a PV system. Faults do not only reduce efficiency but are also detrimental to the life span of a system. Output can be greatly affected by PV technology, configuration, and other operating conditions. Thus, it is important to consider the impact of different PV configurations and materials for thorough analysis of faults. This paper presents a detailed investigation of faults including non-uniform shading, open circuit and short circuit in different PV interconnections including Series-Parallel (SP), Honey-Comb (HC) and Total-cross-Tied (TCT). A special case of multiple faults in PV array under non-uniform irradiance is also investigated to analyze their combined impact on considered different PV interconnections. In order to be more comprehensive, we have considered monocrystalline and thin-film PV to analyze faults and their impact on power grids. Simulations are conducted in MATLAB/Simulink, and the obtained results in terms of power(P)–voltage(V) curve are compared and discussed. It is found that utilization of thin-film PV technology with appropriated PV interconnections can minimize the impact of faults on a power grid with improved performance of the system.

Slot-die processing and encapsulation of non-fullerene based ITO-free organic solar cells and modules

Organic photovoltaic (OPV) devices have shown remarkable performance progress in recent years, reaching current record power conversion efficiency (PCE) values of 16.4% for single junction and 17.3% for multi junction devices, owing mostly to the impressive developments made within synthesis of new non-fullerene acceptors. This progress places organic solar cells at the forefront of thin-film photovoltaic technology. However, in order to meet industrial demands and reach high performance values in industrial settings, further research and development efforts within roll-to-roll (R2R) and sheet-to-sheet (S2S) processing of OPV devices under ambient conditions are required. Furthermore, OPV modules being manufactured through such up-scaled processing techniques should ideally be developed from low cost materials, and show good stability towards various different operational stress conditions. In this work, we demonstrate combined R2R and S2S development of ITO-free OPV devices, which are based on the non-fullerene material system PBDB-T:ITIC. The devices are processed from R2R vacuum sputtering and S2S slot-die coating at ambient conditions, and reach cell PCE values of 5.5%. In addition, we introduce a correlation between different barrier films, both commercial and sputtered inorganic coatings on ultra-clean PET, and the lifetime of the developed devices. The results therefore demonstrate an important step in the development of OPV devices from R2R and S2S processes in industrial settings.

Concept for a Gossamer solar power array using thin-film photovoltaics

In recent years, the German Aerospace Center (DLR) developed Gossamer deployment systems in different projects. As power requirements of spacecraft are getting more and more demanding, DLR recently focused on the development of new deployable photovoltaic (PV) technologies that are suitable for generating 10’s of kW per array. Possible space applications that may also require high power supply are missions using electric propulsion such as interplanetary missions, placing of geostationary (GEO) satellites in their orbit or even more future oriented as space tugs or lightweight power generation on extra-terrestrial infrastructures. The paper gives an overview about a feasibility study for flexible solar arrays based on new thin-film photovoltaics. It is expected that the combination of new thin-film PV technologies, e.g., copper indium gallium selenide (CIGS) cells or gallium–arsenide (GaAs) cells, together with Gossamer deployment technologies, could significantly increase the power availability for spacecraft. Based on a requirement, analysis system concepts were evaluated. A focus is on the potential of CIGS PV combined with a two-dimensional deployment of the array and DLR’s coilable carbon fibre-reinforced plastic (CFRP) booms. Therefore, a concept based on crossed booms with a foldable PV membrane is considered as baseline for further developments. The array consists of rectangular PV generators that are interconnected by flexible printed circuit board (PCB) harness. By a double-folding technique, these generators are laid on top of each other in such that the membrane can be extracted from its stowing box during the deployment in a controlled manner. Considering constantly increasing efficiencies of the CIGS PV combined with Gossamer structures, there is clear potential of reaching a very high specific power value exceeding that of conventional PV systems. Furthermore, the CIGS PV appears to be more radiation resistant and has already reached more than 21% efficiency in laboratories. Such efficiencies are expected to be achieved in the near future in a standard manufacturing process. However, flexible, thin-film GaAs cells are also subject of consideration within GoSolAr. With this prospect, DLR’s research has the goal to develop a Gossamer Solar Array (GoSolAr) to exploit the described potential.

Long Range Battery-Less PV-Powered RFID Tag Sensors

Communication range in passive Radio-Frequency Identification (RFID) front-end devices is a critical barrier in the real-world implementation of this low-cost technology. Purely passive RFID tags power up by harvesting the limited RF energy transmitted by the interrogator, and communicate by backscattering the incident signal. This mode of communication keeps manufacturing costs below a few cents per tag, but the limited power available at the tag undermines long-range deployment. In this paper, we present an approach to use Photovoltaics (PV) to augment the available energy at the tag to improve read range and sensing capabilities. We provide this extra-energy to the RFID integrated circuit (IC) using minimum additional electronics yet enabling persistent sensor-data acquisition. Current and emerging thin-film PV technologies have significant potential for being very low-cost, hence eliminating the barrier for implementation and making of PV-RFID wireless sensors. We reduce the long-range PV-RFID idea to practice by creating functional prototypes of i) a wireless building environment sensor to monitor temperature, and ii) an embedded tracker to find lost golf balls. The read range of PV-RFID is enhanced 8 times compared to conventional passive devices. In addition, the PV-RFID tags persistently transmit large volumes of sensor data (>0.14 million measurements per day) without using batteries. For communication range and energy persistence, we observe good agreement between calculated estimates and experimental results. We have also identified avenues for future research to develop low-cost PV-RFID devices for wireless sensing in the midst of the other competitive wireless technologies such as Bluetooth, Zigbee, Long Range (LoRa) backscatter etc.

Atomic-level passivation mechanism of ammonium salts enabling highly efficient perovskite solar cells

The high conversion efficiency has made metal halide perovskite solar cells a real breakthrough in thin film photovoltaic technology in recent years. Here, we introduce a straightforward strategy to reduce the level of electronic defects present at the interface between the perovskite film and the hole transport layer by treating the perovskite surface with different types of ammonium salts, namely ethylammonium, imidazolium and guanidinium iodide. We use a triple cation perovskite formulation containing primarily formamidinium and small amounts of cesium and methylammonium. We find that this treatment boosts the power conversion efficiency from 20.5% for the control to 22.3%, 22.1%, and 21.0% for the devices treated with ethylammonium, imidazolium and guanidinium iodide, respectively. Best performing devices showed a loss in efficiency of only 5% under full sunlight intensity with maximum power tracking for 550 h. We apply 2D- solid-state NMR to unravel the atomic-level mechanism of this passivation effect.

Interfacial Effects during Rapid Lamination within MAPbI3 Thin Films and Solar Cells

Although hybrid halide perovskite solar cells (PSCs) have recently reached record efficiency among thin film photovoltaic technologies, the stability of these devices remains a pressing problem for...

Investigation of Mo films deposited on high temperature polyimide substrate by magnetron sputtering for flexible CIGS thin film solar cells application

CuIn(1-x)GaxSe2 (CIGS) is one of the most promising thin film photovoltaic technologies for commercial application. Flexible Polyimide (PI) substrate based CIGS solar cells have lots of advantages such as lightness, flexibility, shatter resistance, and so on. However, due to the low glass transition temperature of the commercial PI substrate, the performances of flexible CIGS solar cell and module are much lower than that of CIGS solar cell and module on rigid glass substrate. In this study, we report a two-step process for preparation of PI with high decomposition temperature (Td) and 5% weight loss temperature (Td,5) of 551 and 596 °C, respectively. In addition, Mo films were deposited on the high temperature PI substrate by magnetron sputtering. The effect of deposition pressure on the growth rate, resistivity, microstructure, and surface morphologies of the magnetron sputtering deposited Mo film were investigated. We have shown the Mo coated high temperature PI films has the potential for substrate application in high efficiency flexible CIGS solar cell fabrication.

Thermal Modeling and Performance Evaluation of Photovoltaic Thermal (PV/T) Systems: A Parametric Study

ABSTRACTConventional solar photovoltaic (PV) module converts the light component of solar radiation into electrical power, and heat part is absorbed by module increasing its operating temperature. Combined PV module and heat exchanger generating both electrical and thermal powers is called as hybrid photovoltaic/thermal (PV/T) solar system. The paper presents the design of a PV/T collector, made with thin film PV technology and a spiral flow absorber, and a simulation model, developed through the system of several mathematical equations, to evaluate the performance of PV/T water collectors. The effect of various parameters on the thermal and electrical efficiency has been investigated to obtain optimum combination of parameters. Finally, a numerical simulation has been carried out for the daily and annual yield of the proposed PV/T collector, and comparison with a standard PV module is discussed.

Progress and Perspectives of Thin Film Kesterite Photovoltaic Technology: A Critical Review.

The latest progress and future perspectives of thin film photovoltaic kesterite technology are reviewed herein. Kesterite is currently the most promising emerging fully inorganic thin film photovoltaic technology based on critical raw-material-free and sustainable solutions. The positioning of kesterites in the frame of the emerging inorganic solar cells is first addressed, and the recent history of this family of materials briefly described. A review of the fast progress achieved earlier this decade is presented, toward the relative slowdown in the recent years partly explained by the large open-circuit voltage (VOC ) deficit recurrently observed even in the best solar cell devices in the literature. Then, through a comparison with the close cousin Cu(In,Ga)Se2 technology, doping and alloying strategies are proposed as critical for enhancing the conversion efficiency of kesterite. In the second section herein, intrinsic and extrinsic doping, as well as alloying strategies are reviewed, presenting the most relevant and recent results, and proposing possible pathways for future implementation. In the last section, a review on technological applications of kesterite is presented, going beyond conventional photovoltaic devices, and demonstrating their suitability as potential candidates in advanced tandem concepts, photocatalysis, thermoelectric, gas sensing, etc.

Role of Na and Ca as Isovalent Dopants in Cu2ZnSnS4 Solar Cells

A pathway to improve the efficiency of Cu2ZnSnS4 (CZTS)-based solar cells, which form an important class of beyond-Si, thin-film photovoltaic technology, is the employment of sustainable isovalent dopants (substituting for Cu and Zn) to suppress formation of disorder-inducing, performance-limiting antisite defects. Using calculations based on density functional theory, we examine the influence of Na and Ca as isovalent dopants for Cu and Zn, respectively, on defect formation, thermodynamic stability, and electronic properties of CZTS. On the basis of defect formation energies, we find that Na-doping should be feasible within CZTS while the incorporation of Ca will be difficult. Importantly, both Na and Ca effectively mitigate formation of antisites that cause disorder, if incorporated within the CZTS structure, across doping and Cu-chemical-potential conditions. Thermodynamically, doping high concentrations of Na into CZTS will result in phase separation between CZTS and Na2ZnSnS4 domains, whereas large a...

Quantum and Dielectric Confinement Effects in Lower-Dimensional Hybrid Perovskite Semiconductors.

Hybrid halide perovskites are now superstar materials leading the field of low-cost thin film photovoltaics technologies. Following the surge for more efficient and stable 3D bulk alloys, multilayered halide perovskites and colloidal perovskite nanostructures appeared in 2016 as viable alternative solutions to this challenge, largely exceeding the original proof of concept made in 2009 and 2014, respectively. This triggered renewed interest in lower-dimensional hybrid halide perovskites and at the same time increasingly more numerous and differentiated applications. The present paper is a review of the past and present literature on both colloidal nanostructures and multilayered compounds, emphasizing that availability of accurate structural information is of dramatic importance to reach a fair understanding of quantum and dielectric confinement effects. Layered halide perovskites occupy a special place in the history of halide perovskites, with a large number of seminal papers in the 1980s and 1990s. In recent years, the rationalization of structure-properties relationship has greatly benefited from new theoretical approaches dedicated to their electronic structures and optoelectronic properties, as well as a growing number of contributions based on modern experimental techniques. This is a necessary step to provide in-depth tools to decipher their extensive chemical engineering possibilities which surpass the ones of their 3D bulk counterparts. Comparisons to classical semiconductor nanostructures and 2D van der Waals heterostructures are also stressed. Since 2015, colloidal nanostructures have undergone a quick development for applications based on light emission. Although intensively studied in the last two years by various spectroscopy techniques, the description of quantum and dielectric confinement effects on their optoelectronic properties is still in its infancy.

Advances in Solution‐Processed Multijunction Organic Solar Cells

The efficiency of organic solar cells can benefit from multijunction device architectures, in which energy losses are substantially reduced. Herein, recent developments in the field of solution-processed multijunction organic solar cells are described. Recently, various strategies have been investigated and implemented to improve the performance of these devices. Next to developing new materials and processing methods for the photoactive and interconnecting layers, specific layers or stacks are designed to increase light absorption and improve the photocurrent by utilizing optical interference effects. These activities have resulted in power conversion efficiencies that approach those of modern thin film photovoltaic technologies. Multijunction cells require more elaborate and intricate characterization procedures to establish their efficiency correctly and a critical view on the results and new insights in this matter are discussed. Application of multijunction cells in photoelectrochemical water splitting and upscaling toward a commercial technology is briefly addressed.

Copper Chalcopyrites for Solar Energy Applications

Solar photovoltaic (PV) technology is a reliable and environmental friendly alternative for electricity generation. There are a number of solar PV technologies at different maturity levels, ranging from well-established and commercialized silicon PV to still in conceptual and R&D phase quantum dot and organic/polymer solar cells. Chalcopyrite solar cells, named so because of the thin absorber layer of Cu-based chalcopyrite materials used in these cells, are one of the frontrunners in thin-film PV technology owing to their tunable direct bandgap, large absorption coefficient and long-term stability. Among all Cu-chalcopyrite materials, copper indium selenide (CISe) and copper indium gallium selenide (CIGSe) are most suitable for use as light-absorbing layer. Although CISe and CIGSe absorber-based PV modules are being produced commercially for several years now, the technology is yet to mature fully as there is still scope for improvement in efficiency, manufacturability and cost reduction. The present article discusses the status of CISe-/CIGSe-based thin-film PV technology while primarily focusing on the absorber material. Different vacuum and non-vacuum methods for fabricating these materials are reviewed along with their merits/demerits and suitability to large-scale production. Current status of commercial maturity for CIGSe PV is discussed while providing general process details of selected industrial manufacturers. Existing bottlenecks for this technology are deliberated, and future directions for improvement in laboratory-scale efficiency and manufacturability are outlined.

From Laboratory to Production: Learning Models of Efficiency and Manufacturing Cost of Industrial Crystalline Silicon and Thin-Film Photovoltaic Technologies

Efficiency and manufacturing cost are two key elements for the photovoltaic (PV) industry. In this paper, we look at the time-dependent evolution of efficiency and manufacturing cost for PV devices. For efficiency improvements, the empirical model developed by Goetzberger et al. is applied to describe the time-dependent improvements for a concrete technology in laboratory cell's research and development, and the learning factor c is extracted. The application of the Goetzberger's model is extended to industrial PV modules. It is forecasted that cadmium telluride (CdTe) and copper gallium indium diselenide (CIGS) will have the average module efficiency in 2020 of 17.9% and 16.4%, respectively. Over 21.8% commercial module efficiency is projected with n-type Si interdigitated back contact technology, while average module efficiencies of 17.4%, 18.4%, and 19.4% are projected for conventional p-type multi-, mono-, and mono-passivated emitter and rear cell (PERC), respectively. For the manufacturing cost, we parameterized the learning curve model of manufacturing cost for industrial crystalline silicon (c-Si), CdTe, and CIGS technologies. As projected by the learning curve, the manufacturing cost of c-Si and thin-film modules may reach 0.2 $/Wp or below, when the cumulative production reach 1 TW. The learning rate for Si (24.2%) is greater than CdTe (19.1%) and CIGS (8.1%).

Comparing the potential of different strategies for colour tuning in thin film photovoltaic technologies

ABSTRACTWhile the performance of some emerging solar cell technologies is rocketing, there are other important parameters that also need to be considered for industrialization, including aesthetics, payback time or long-term stability. More specifically, aesthetical features of the solar cells play a very important role in the path towards the integration of these semi-transparent technologies into the buildings and windows of the future. In this work, we have implemented a theoretical methodology to study in depth colour tuning in polymer-based organic photovoltaic cells that uses experimentally complex refractive indices. We compare quantitatively basic interference effects (through active layer thickness), binaries with different donors and different acceptors, and ternary systems where the third component is either active or a simple dye. For hybrid perovskite solar cells, we compare the colour tuning capability of blending and alloying. Additionally, we show that the same theoretical framework can be employed for the so-called inverse problem, i.e. determining the best solar cell parameters (specific materials, donor:acceptor ratio and photoactive film thickness) that can reproduce a desired set of chromaticity coordinates.

Comprehensive studies of air-brush spray deposition used in fabricating high-efficiency CH3NH3PbI3 perovskite solar cells: Combining theories with practices

Organic-inorganic perovskite solar cells (PSCs) are among the most attractive and efficient emerging thin film photovoltaic technologies. The perovskite films have been fabricated by lots of deposition methods, including one-step/two-step spin coating, thermal evaporation and vapor assisted processes. However, the laboratory-based fabrication methods are not well matched with large area manufacture for actual use. Spray coating deposition technique is being explored to prepare perovskite films to break the bottleneck plaguing large scale production. Herein, a comprehensive study is conducted in fabricating perovskite films by air-brush spraying method. The spraying process is classified into three stages, namely, 1) atomization process, 2) droplet flight and 3) film deposition. Each of them is discussed in detail from principles to parameters. Integrating the three aspects above, high quality perovskite films comparable to spin coated films are obtained. A best power conversion efficiency (PCE) of 16.68% is achieved for planar structure PSCs, which is prominent among the PSCs fabricated by spraying method. In addition, devices with spraying method show excellent optical and electrical properties. The principles we discuss here could be applied in the actual condition for mass production.

Thin film photovoltaic devices prepared with Cu3BiS3 ternary compound

Current commercial thin film photovoltaic technologies rely on the use of scarce and/or toxic elements, motivating the necessity to explore new technologies free of critical raw materials. In this work we report the first Cu3BiS3 based solar cells with proved photovoltaic activity using standard substrate configuration. The absorbers were synthesized using a sequential process based on metallic stacks evaporation followed by a reactive annealing under S atmosphere. With the optimization of composition (Cu/3: Bi ratio), metallic stack order, annealing parameters and Na doping, we achieve a record conversion efficiency of 0.11%. Combining several characterizations techniques, we show that at this stage of the technology development, issues like composition, secondary phases and morphology cannot explain the low efficiencies obtained with this material. Through a deeper characterization of the devices, we found that most probably, this is related to either, a high doping of the absorber, and/or poor transport charge properties. Understanding and solving these issues, can further help to improve the efficiency of Cu3BiS3 based devices towards more competitive conversion efficiencies.

Giant optical pathlength enhancement in plasmonic thin film solar cells using core-shell nanoparticles

In this paper, a finite-difference time-domain method is adopted to investigate the light scattering properties of core (metal)-shell (dielectric) nanoparticles, with varying shell thickness and refractive index. Adding a shell coating can shift the resonance to above the solar material bandgap when compared with a bare nanoparticle that has resonance outside of the useful solar radiation. The front-located core–shell metal-dielectric nanoparticles on thin Si substrates demonstrate enhanced forward scatterings with suppressed backward scatterings. The fraction of light scattered into the substrate and the maximum optical path length enhancement can be as high as 0.999 and 3133, respectively, if properly engineered, while the maximum optical path length enhancements of an ideal Lambertian and dipole source are only ~100. This light scattering property can be ascribed to the constructive interference of the electric and magnetic dipoles. The giant fraction of light scattered into the substrate and the maximum optical path length enhancement in core–shell nanoparticle based plasmonic solar cells provides an insight into addressing the out-coupling and poor pathlength in thin film photovoltaic technology.

Thin-Film And Crystalline Photovoltaic Modules – Outdoor Performance And Economic Estimation

Thin film photovoltaic (PV) technologies were quite popular in 2005-2010 due to relatively low modules costs and low need in silicon or other materials. Amorphous silicon (a-Si) thin films are well known as PV active material with wider light absorption bandgap than for crystalline silicon which allows better module operation in case of diffuse radiation. Low PV energy conversion efficiency (7-11% against 16-19% for crystalline) is a main drawback of such modules. CuInGaSe2 (CIGS) thin films have no such features for absorption bandgap, but have large efficiency (13-14% for PV module and 20,4% for laboratory scale cell). It is also known, that thin film modules have much lower temperature power coefficient, which makes their operation more reliable at hot weather. Nowadays fast progress in crystalline silicon PV technologies led to lower cost for crystalline modules and made thin film technologies less competitive. In Joint Institute for High Temperatures comparative field tests of several thin film and crystalline modules were conducted in 2015-16, using small autonomous power units (PV module, charge controller, small accumulator for charge controller feed and resistive load) as a test bed. Specific energy production for each module throughout different months and the whole test period (10.2015-10.2016) was used as a main criteria for comparison. Economic efficiency (energy production to capital costs ratio for each module type) was also estimated.