ABSTRACT Tin‐based halide perovskites have emerged as environmentally benign alternatives to lead‐based counterparts for next‐generation photovoltaics. This study presents the design and optimization of dual‐absorber perovskite solar cells with the architecture ITO/ETL/GA x (FA 0.8 Cs 0.2 ) 1‐x SnI 2 Br/(CsSnI 3 /MASnI 3 /FASnI 3 )/HTL/Au. The proposed structure strategically integrates a wide‐bandgap top absorber with three narrow‐bandgap bottom absorbers to achieve complementary light harvesting and enhanced charge generation and collection. Device simulations using SCAPS‐1D involved systematic optimization of absorber layer thickness, defect densities, interfacial properties, charge transport layers, operating temperature, and back contact work function. The FASnI 3 cell achieved Voc of 1.04 V, Jsc of 29.77 mA/cm 2 , FF of 83.81%, and PCE of 26.05%. For MASnI 3 , Voc was 1.01 V, Jsc 33.59 mA/cm 2 , FF 85.78%, and PCE 29.00%. The CsSnI 3 device delivered the best performance with Voc of 0.99 V, Jsc 34.88 mA/cm 2 , FF 86.00%, and PCE 29.64%. Analyses including Mott–Schottky profiling, recombination mapping, J‐V curves, QE, and capacitance studies provided insights into device physics. TiO 2 emerged as the most suitable electron transport layer due to favorable band alignment, while CuSbS 2 served as an effective hole transport layer. These results highlight the potential of lead‐free, tin‐based dual‐absorber perovskite solar cells as efficient and sustainable candidates for future photovoltaic technologies.
Photovoltaic (PV) production grows rapidly in the Nordics, but literature on calculating long-term PV performance losses remains limited in these conditions, leading to inaccurate yield estimations and economic losses. To fill this knowledge gap, this contribution (1) shows typical PV performance characteristics, (2) obtains performance loss rates (PLRs) from multiple systems, and (3) assesses the best practices of PLR calculation under these conditions. For these objectives, we compared various methods for all steps of PLR calculation, including data filters, performance metrics, aggregation intervals, and statistical models for five systems (with 2.5-6 years of data) across Finland, from 60 degrees to 67 degrees N. Dark winters and snow coverage caused gaps and anomalies to the performance time series during wintertime, resulting in unrealistic PLRs. Excluding these anomalies with performance threshold filter improved the results. As the different methods can drastically affect the PLR value, an ensemble method consisting of an assessment of average PLR with over 700 calculation approaches was validated to be essential in identifying robust PLRs. Using this ensemble method, the system PLR estimates ranged from 0.41%/year to 2.65%/year. The data and codes are made publicly available, contributing to open access of PV datasets and allowing wider application of the PLR methodology.
Deployment of photovoltaics in space requires devices that combine high-efficiency, low areal mass, and resilience to harsh environments. Historically, high-efficiency multijunction III-V materials have dominated space power systems; however, their high cost and limited manufacturing throughput motivate the exploration of scalable alternatives. While CdTe-based thin-film photovoltaics offer an attractive option, their performance on non-conventional substrates can suffer from front contact instability under higher-temperature processing. Here, the role of front contact chemistry in limiting cell performance is investigated using CdTe-based devices fabricated on 150 mu m thick Ceria-doped space-qualified 0214 Corning glass. A matrix of four transparent conducting oxides (TCOs: CTO, AZO, ITO, IZO) combined with two n-type emitters (MZO, IGO) reveals chemical stability at the front interface-rather than absorber composition alone-governs recombination losses, voltage deficits, and device reproducibility. Chemically stable front contact combinations suppress elemental diffusion and interfacial degradation, resulting in significantly improved carrier lifetimes and junction quality. These insights are validated through record-certified Cd(Se,Te) cell efficiencies of 18.4% under AM1.5G and 16.2% under AM0 illumination on ultra-thin glass. Beyond CdTe, this work provides a general framework for the rational selection of TCO/emitter interfaces in superstrate thin-film photovoltaics, including emerging technologies like metal halide perovskites, while enabling high-efficiency, lightweight photovoltaics for space applications.
This work investigates the role of Na and Rb incorporation in ultra-thin Cu(In,Ga)Se2 (CIGSe) solar cells, focusing on performance optimization. By systematically varying the Rb content and combining predeposited Na with postdeposited Rb, we identify the optimal configuration, achieving efficiencies of 11.72% on Mo and 10.48% on ITO. Comprehensive structural and electrical characterization reveals that Rb not only enhances the absorber quality through superior grain boundary passivation, following a Na-Rb exchange mechanism, but also modifies the CIGSe/CdS interface by influencing the absorber surface and Cd incorporation. While combined Na and Rb postdeposition treatments suppress Cd incorporation, predeposited Na can promote it. In both cases, the added Na and Rb support the creation of an ordered vacancy compound (OVC) layer, which improves the band alignment. Temperature-dependent IV (IVT) measurements distinguish between interface and bulk recombination, revealing a Schottky barrier originating from possible GaOx formation at the ITO/CIGSe interface, as well as a current-blocking behavior at the CIGSe/CdS interface at low temperatures related to Rb. Tuning the Ga distribution further enhances device performance: An In-Ga-In sequence in the first stage of absorber growth suppresses Rb/CdS-related barriers and further promotes alkali metal incorporation, supporting OVC layer growth and thereby possibly improving band alignment. A mechanistic model showcasing this interplay between Na, Rb, OVC, and Cd is made for visualizing the structural formation during absorber growth. These results underline the relevance of the first systematic Rb analysis in ultra-thin CIGSe solar cells and highlight the synergistic potential of combining alkali metal doping with Ga grading to improve ultra-thin CIGSe solar cells.
Laser-assisted firing (LAF) technologies, such as laser-enhanced contact optimization (LECO), have enabled the reliable application of low-Al Ag pastes for front-side metallization in tunnel oxide passivated contact (TOPCon) solar cells, opening a pathway to improved damp-heat (DH) stability and glass-backsheet (G-B) module designs. To further lower production costs, ethylene-vinyl acetate (EVA) and EVA/polyolefin/EVA (EPE) encapsulants are commonly employed; however, their long-term hydrolytic degradation produces acetic acid, which promotes metallization corrosion. In this work, we systematically investigate the impact of glass frit chemistry in two commercial low-Al content Ag front pastes on the cell- and module-level stability of LAF-processed TOPCon devices. Accelerated acetic-acid exposure tests reveal that a Ba- and Zn-modified glass frit (Paste B) exhibits markedly improved resistance to interfacial degradation compared with a Pb- and B-rich frit (Paste A), as evidenced by a maintained series resistance, contact resistivity and Ag-Si interfacial integrity. Microscopic and elemental analyses revealed that Ba enrichment in the glass frit markedly improves interfacial stability relative to Pb- and B-rich formulations. At the module level, DH85 (85 degrees C/85% RH) testing of G-B TOPCon modules (front EPE/rear EVA) demonstrates that Paste B limits the relative power loss to 4%-5% after 1500 h, whereas Paste A leads to severe fill-factor-driven degradation resulting in a power loss over 25%. These results establish a direct correlation between glass frit composition, acetic-acid corrosion resistance and DH stability, highlighting glass network engineering as a key lever for designing robust, low-cost metallization systems for next-generation TOPCon modules.
If not cleaned, energy loss due to soiling can go up to 50% in 4 months in parts of India. Such losses significantly impact the economic viability of PV deployments in sunbelt countries like the Middle East and India. Antisoiling coating offers a cost-effective dust mitigation strategy. However, as the coating is applied on the outer surface of the PV module, it has to endure various environmental stressors. Our previous studies have shown that rain is one of the most significant stressors that degrade the antisoiling coatings. This study estimates the lifetime of antisoiling coatings when subjected to rain, considering the pH of the rainwater as the stressor. The study was done on four commercial hydrophobic antisoiling coatings (A-D). Coated samples were exposed to water immersion tests; thus, the effect of the impact of the raindrop is not considered in this study. Characteristic times to failure were estimated using the Weibull distribution. The activation energy and pH dependence factor (N) were calculated using the Arrhenius-modified Pecks model. The activation energy of Coatings A-D were calculated to be 0.09, 0.43, 0.09, and 0.56 eV, respectively. Positive activation energy indicated that the coating life decreases with increased temperature. The pH dependence factor (N) for Coatings A-D was estimated as 3.6, 1.4, 0.28, and 1.31, respectively. Based on the modelled equation, we predict the life of the coatings based on Miner's rule at two different locations. All coatings showed lower coating life irrespective of the pH when exposed at a tilt angle lower than their respective roll-off angle. PV plant developers can use these data to predict coating life against this stressor at different locations, which can help identify coatings that work for specific weather conditions. It may also act as the starting point to model the effect of the combination of stressors.
Modern c-Si photovoltaic (PV) cells provide high performance but can be vulnerable to ultraviolet light induced degradation (UV-ID). Encapsulants, if chosen correctly, can mitigate UV-ID of the PV cell. Here, we explore performance and durability of 14 commercial encapsulant materials before, during, and after irradiation with UV-containing light. Materials include contemporary, polymer-based encapsulants with a base polymer of poly (ethylene co-vinyl acetate) (EVA), polyethylene-alpha-olefin (POE), or their composite (EPE). Polymers contain additives that induce UV-blocking, UV-transmitting, or UV-downshifting properties. We use test coupons to study degradation in a chamber held at 65 degrees C under a xenon light source for up to 4000 h of exposure, corresponding to a cumulative dose of 11.5 MJ/m2 at 340 nm. We examine optical properties including spectral transmittance, yellowness index and spectral fluorescence, considering changes to both the encapsulant and glass as a function of weathering time. Degradation modes identified include discoloration, changes to UV cutoff wavelength, changes to solar-weighted transmittance, and most notably a change to the UV-managing properties of some additives. We propose the use of solar-weighted transmittance in the 300- to 400-nm range to better track performance changes in the UV region associated with the UV-related additive. This is especially relevant for the emerging class of UV-downshifting additives, as metrics like UV-cutoff can understate the degree of degradation or change in these materials. While most encapsulants show very little change after weathering, some show significant changes that directly impact how much UV light would reach an underlying cell.
Understanding degradation in perovskite solar modules (PSMs) is crucial for improving long-term stability, yet accessing internal layers without introducing artifacts remains difficult. We present a controlled coring method tailored for PSMs that enables mechanical extraction of intact device sections while preserving their structural, chemical, and optoelectronic properties. Comprehensive characterizations confirm that the cored devices remain representative of the original module, with no detectable artifacts introduced during extraction. Applying this technique to field-aged modules operated outdoors for 10 months reveals nonuniform photoluminescence, bandgap shifts, Ag oxidation, and the alpha-to-delta phase transition of formamidinium lead iodide (FAPbI3), which are clear evidence of moisture-driven Ag corrosion and ion migration at the perovskite/Ag interface. This work establishes a reliable approach for accessing encapsulated perovskite modules and provides direct insight into real-world degradation pathways, offering guidance for improving the durability of perovskite photovoltaic technologies.
This study investigates the optoelectronic characteristics of solar cells based on wide bandgap Cu(In,Ga)S2 (CIGS) absorbers, co-evaporated onto glass substrates covered with 100 nm-thick indium tin oxide (ITO) back contact. Devices based on absorbers with different thicknesses (ranging from 320 to 1580 nm) were investigated. Structural characterizations confirmed that all of the films were made of large grains, crystallized in the chalcopyrite structure with no secondary phases. It has been observed that the performance of the cells with front-side illumination improves with increasing CIGS thickness, mainly because of increased short-circuit current (J SC). In contrast, the opposite trend is observed for rear-side illumination, further suggesting a hindered collection of carriers generated close to the ITO/CIGS interface. The modelling of quantum efficiency using e-ARC tool and Gartner theory suggests that all absorbers, independently of their thickness, are nearly fully depleted. In addition, they all exhibit a region with a low collection of photogenerated carriers at the vicinity of the ITO/CIGS interface. It is proposed that this area results from the consumption of gallium during gallium oxide formation at the ITO/CIGS interface.
Perovskite solar cells (PSCs), particularly cesium lead iodide (CsPbI3)-based ones, offer low fabrication costs, high efficiency, and potential for scalable production. However, a significant drawback is their instability, especially under moisture and high-temperature conditions, which can lead to degradation and reduced long-term performance. To overcome these issues, this paper presents a novel approach for optimized three-layer carbon electrode (CE) architecture for high-performance CsPbI3 PSCs. The proposed method integrates the capabilities of leaf in wind optimization (LWO) algorithm and progressive graph convolutional networks (PGCNs), forming a model termed LWO-PGCN. The main goals of the proposed technique are to develop the power conversion efficiency (PCE) and stability of PSCs. The LWO algorithm performs global optimization of structural parameters, while the PGCN model predicts photovoltaic performance by capturing complex relationships between device parameters, enabling efficient identification of high-performance device configurations. The LWO algorithm is employed to optimize perovskite layer thickness, hole transport material (HTM) layer thickness. The PGCN is used to predict the PCE with high accuracy. The proposed method demonstrates better performance than existing techniques, including deep neural network (DNN), probabilistic neural networks (PNN), and artificial neural network (ANN), as evaluated and compared using the MATLAB platform. The proposed method achieves a higher PCE of 29.9%, short-circuit current density (J sc) of 25.84 mA/cm2, open-circuit voltage (V oc) of 1.32 V, and fill factor (FF) of 74.89%, indicating superior photovoltaic performance compared with existing methods. The proposed LWO-PGCN model significantly enhances the stability and efficiency of CsPbI3-based PSCs, outperforming existing methods in photovoltaic performance.
Wide-gap Cu(In,Ga)S2 solar cells with In2O3:Sn (ITO) as transparent back contact are evaluated for the application as top cells in tandem devices. The effect of Na on the solar cell performance is investigated by supplying additional Na by NaF co-evaporation or exclusively by Na diffusion from glass. An efficiency of 12.7% is achieved for a semitransparent solar cell with a band gap of 1.6 eV, with sufficient Na diffusion from glass only, allowed by a thin ITO layer. Absorber grown with additional NaF co-evaporation during Cu(In,Ga)S2 growth on thicker ITO show a comparable efficiency of 12%. High-temperature growth at = 630 degrees C enhances overall absorber quality and results in wide-gap absorbers, with photoluminescence quantum yield improved to 1.5 & times; 10-5, two orders of magnitude higher than absorber grown at low temperature. NaF co-evaporation is effective in suppressing deep defects, thereby reducing non-radiative recombination and enhancing photoluminescence quantum yield further. A GaOx interfacial layer is formed at the rear contact, likely contributing to the passivation of the back contact. With the presence of thick GaOx layer, current blocking effects are visible in the current-voltage curves. On the contrary, a thinner ITO tends to result in thinner GaOx layer and no current blocking is observed.
The unprecedented growth of satellite constellations in Low Earth Orbit (LEO) triggers a need for cost efficient solar generators able to meet a larger demand. High interconnection reliability is one of the requirements for LEO application where systems are exposed to up to large amplitude thermal cycles per year. Standard terrestrial cell to wire/ribbon interconnections are not reliable enough. In the present work, we report the electrical performance of strings of 90-m-thick heterojunction (HJT) and 160-m-thick passivated emitter and rear cell (PERC) cells exposed to thermal cycles with an amplitude of 120 degrees C/120 degrees C based on IV curve measures at room and higher temperature along with electroluminescence and lock in thermography imaging. Shingle strings were fabricated with two different electrically conductive adhesives (ECA) for their tile-to-tile interconnection (TTI) and another for the interconnection-piece-to-tile interconnection (IPTI) prior to their encapsulation. All string materials and processes are based on the terrestrial photovoltaic (PV) industry. The results highlight the existence of interconnection instabilities, which can cause power losses underestimations. Nevertheless, all strings withstand thermal cycles and some thermal cycles with a maximum power loss of . The best strings present no sign of TTI degradation after thermal cycles. These results unveil the great potential of shingle for LEO applications.
This study presents a comparative analysis of three major failure modes in n-type photovoltaic modules-hotspot effects, ultraviolet-induced degradation (UVID), and potential-induced degradation (PID)-to address critical reliability concerns. Using standardized IEC testing protocols, we systematically evaluated multiple module technologies. Key findings reveal the following: (1) the correlation between technological configurations and hotspot temperature distribution under extreme shading conditions; (2) the relative susceptibility of tunnel oxide passivating contact (TOPCon), heterojunction with intrinsic thin-layer (HJT), and back-contact (BC) prototypes to UVID; and (3) distinct PID mechanisms and degradation pathways at the front versus rear surfaces across different architectures. The results provide essential theoretical and empirical insights to support the development of more reliable photovoltaic products.
This study investigates the dynamics of hydrogen in p-type silicon semiconductors, with a particular focus on the influence of excess minority carriers on hydrogen reactions. Our findings reveal that the presence of these carriers significantly increases atomic hydrogen concentration due to enhanced acceptor-hydrogen dissociation. We propose a unified model that effectively describes the behavior of hydrogen species under both thermal equilibrium and non-equilibrium conditions in both B- and Ga-doped Si. This model provides a coherent explanation for phenomena associated with Light- and Elevated Temperature-Induced Degradation (LeTID) during dark annealing and light soaking processes. We believe that any light soaking process in the photovoltaic industry causes hydrogen-related effects, even if unintentional. This understanding is pivotal for optimizing light soaking processes, ultimately improving defect and surface passivation and enhancing the efficiency of silicon solar cells.
Silicon solar cells are currently expected to resume into the space market especially for the low earth orbit constellations in the dawning commercial spaceflight industry throughout the world. In this paper, the commercial p-type wafers are used, and the front emitter silicon heterojunction (SHJ) solar cells with 100 mu m thickness are prepared. These cells are treated with 1 MeV electron irradiation of various fluence. The degradation performances of SHJ cells are analyzed, it is found that the degradation rates of the SHJ cell efficiency are around 22.5% and 26.6% at 5.0 & times; 1013 and 1.0 & times; 1014 e/cm2, respectively, which is mainly attributed to the open-circuit voltage degradation. Furthermore, the deep level transient spectroscopy (DLTS) measurements indicated that the high concentration defects at the deep levels of EV + 0.36 eV and EV + 0.18 eV within energy band of the crystalline silicon act as the traps and recombination centers to deteriorate the carrier diffusion length and the open-circuit voltage of the irradiated SHJ solar cells. Fortunately, 96 h-light soaking under AM0 at room temperature and further 20-min annealing treatment at 150 degrees C in open circuit condition under nitrogen allows SHJ solar cells to create a recovery, and the degradation rates come down to around 18.6% and 23.2% with the electron irradiation fluences of 5.0 & times; 1013 and 1.0 & times; 1014 e/cm2 at 1 MeV, respectively. In fact, this post-treatment process is similar to the on-orbit operating state of a satellite, the solar cells temperature would sharply increase when solar panels face the sun. This self-healing can partially mitigate the radiation-induced degradation of SHJ solar cell.
The integration of PV modules into the building envelope requires new module concepts in order to increase their acceptance and their integrability into standard processes of the building industry. In this work, we develop prototypes of a PV-activated design fa & ccedil;ade element with aluminum as base material. We investigate various designs, ranging from flat aluminum sheets to folded sheets and fa & ccedil;ade elements with a design structure. The PV module is always laminated directly onto the aluminum sheets and fa & ccedil;ade elements. The large difference in thermal expansion coefficients of glass and aluminum is a challenge for the production of such PV-activated fa & ccedil;ade elements. It leads to bending of the modules after lamination. However, PV-modules built on the design structures do not bend. We therefore focus on that type of fa & ccedil;ade elements for developing the prototype. The electrical insulation between the current-carrying solar cell strings and the aluminum fa & ccedil;ade element is another challenge. The use of anodized aluminum and using an additional polyvinyl fluoride layer resolves this issue. The measurement of the insulation resistance both in dry and wet conditions results in insulation resistances similar to that of standard glass-backsheet PV modules, when measured according to IEC 61215. We show different design variants of our PV-activated design fa & ccedil;ade element, which demonstrates the variability in appearance and will thus hopefully support a wider spread of building-integrated photovoltaics (BIPV).
