Progress in Photovoltaics最新文献

Organometallic halide perovskites have received significant attention due to their promising optoelectronic properties, particularly in photovoltaics. The formation process of perovskite films is crucial in determining their structural and functional characteristics. In this study, the effects of methylamine vapour treatment and vacuum annealing on enhancing the crystallinity, morphology and structural integrity of perovskite films are examined. Methylammonium lead iodide (MAPI)–based perovskite films are investigated, with a focus on their crystallographic structure, vibrational modes and their correlation with device performance. Power conversion efficiencies (PCEs) of 19.5% and 18.6% have been achieved using one-step and two-step processes, respectively. The influence of trap states, film homogeneity and interfacial properties has been analysed through capacitance, photoluminescence and electroluminescence measurements, with recombination behaviour linked to crystallographic properties. These findings provide valuable insights into the role of processing techniques in the rejuvenation of perovskite solar cells. Additionally, they offer guidance for optimising fabrication strategies to improve film quality, device performance, stability and long-term reliability.

Alternating current (AC) PV modules offer several advantages such as easier installation, safer operation and increased efficiency for residential and building-integrated PV systems including small balcony power plants. We therefore expect a growing market for AC modules. We present a combination of different innovations to demonstrate the potential for synergies and simplifications when fully integrating power electronics into PV modules. Our module features a novel, highly efficient and compact power electronics with galvanic isolation. The fully reactive power-capable inverter topology utilizes 650 V gallium nitride power semiconductors. The communication is enabled by wireless communication based on Wirepas mesh connectivity, allowing a safe and robust operation and flexible expansion of the PV system. The module electronics are connected directly to the cross-connectors of the PV modules, enabling novel circuit configurations that eliminate the need for conventional bypass diodes. Our approach is cost-effective and limits the operating range of each substring to prevent hot spot events on the module. Furthermore, a slot antenna is introduced into a cross-connector of the PV module. The antenna is capacitively fed through the backsheet by an aperture coupling printed circuit board (PCB) on the rear side of the module. The fully integrated electronics are attached to the PV module, encapsulated and electrically isolated from the environment by low-pressure molding, which has shown high reliability in accelerated aging tests. All these key components are combined in full-sized PV demonstrator modules that we install and operate on an outdoor test stand to prove the functionality of all the combined components.

The market uptake of silicon heterojunction (SHJ) solar modules is projected to increase rapidly, which is expected to play a significant role in future sustainability. However, a major barrier to the mass production of SHJ solar modules is significant power degradation under ultraviolet (UV) irradiation. Here, we reported a 98.13% high-quantum yield and highly reliable CaSrSiO₄:Ce³⁺ UV-to-blue–violet downshifting (UV-DS) inorganic phosphor for photovoltaic applications, which could minimize UV-induced degradation, the levelized cost of energy, and the generation of photovoltaic module waste. The CaSrSiO₄:Ce³⁺ inorganic phosphor was synthesized via a solid-state reaction method, where Ce³⁺ ions preferentially occupy the 7-coordinated Ca site. As a proof of concept, an outstanding output power of 776.2 W and a module efficiency of 24.99% were achieved on 3.1 m² industrial-scale module. Only 2.49% power degradation was observed after 180 kWh/m² UV irradiation. A statistical lifetime assessment based on UV irradiance data of Chinese geographical locations proven that UV-DS encapsulants significantly enhanced the long-term stability of modules, with better power generation performance and economic and environmental characteristics. Our study offered a blueprint for designing SHJ photovoltaic modules sustainably and strategically for targeting geographic markets, mitigating one of the environmental risks associated with SHJ modules and accelerating practical application.

This work aims to define the optimization criteria for Cu(In,Ga)Se₂ (CIGS) as a bottom cell in a tandem structure, and to emphasize the differences from optimizing the CIGS when operating alone. Reproducing the single-cell recipes and only lowering the band gap is insufficient to optimize the bottom cell. We identified that the lack of high-energy photons, which are absorbed by the top cell, can cause a severe fill factor (FF) loss, and thus diminish the photovoltaic performance. With nonoptimized buffer layers (CdS and ZnMgO), S-shaped current-density-voltage (JV) characteristics leading to a low FF and poor performance can be observed. The S shape can be eliminated within seconds of white-light exposure and does not return for hours. Therefore, this does not pose a significant problem for single-cell operation. In the bottom-cell application, as only the low-energy part of the spectrum is available, the properties of the buffer layer(s) become crucial and additional optimization is necessary. Filtered JV measurements after white-light exposure could lead to overseeing important optimization steps. We discuss the causes for an S-shaped curve under filtered illumination, pinpoint the bottlenecks in the bottom-cell performance, and present a way to mitigate the losses.

Accelerated aging was used to assess environmental degradation in emerging co-extruded polypropylene (PP)-based backsheets under three different environmental conditions (65°C/20% relative humidity (RH), 75°C/20% RH, and 75°C/50% RH). Although differential scanning calorimetry did not measure crystallinity changes with exposure, spatially resolved Raman spectroscopy identified crystallinity increases in the core layer of aged samples, indicating a heterogeneous postcrystallization process. The Raman results were in agreement with synchrotron-based microfocused wide-angle X-ray scattering measurements. Cross-sectional nanoindentation was used to correlate localized crystallinity shifts with changes in Young's modulus. A similar trend was found where increased modulus was measured in the core layer, supporting the relationship between modulus and crystallinity. Finally, dielectric characterization was used to assess the impact of these material property changes on performance. While changes in the backsheet material properties and dielectric performance were observed with accelerated aging, these shifts generally equilibrated with time, indicating overall stability in response to environmental stressors. Additionally, the identified heterogeneous material property changes indicate that spatially resolved crystallinity measurements may be a valuable early failure indicator to be used in the assessment of PV backsheet long-term durability.

Silicon (Si) heterojunction (SHJ) solar cells are today a mature industrial technology allowing the highest efficiency of Si single junction cells. Nevertheless, SHJ efficiency dispersion related to the wafer quality (Si minority carrier lifetime, τ_bulk) can be up to 1%_abs with the present specification of high quality n-type Cz. Thus, in order to enhance the quality of the wafers, several low-cost annealing processes on as-cut wafers performed under air atmosphere before entering cell line have been tested. Results suggest that multiple factors are involved in the change of τ_bulk. At low temperature (< 500°C), all wafers carrier lifetime improved significantly whereas at high temperature (> 700°C) their quality degrades. In the intermediate temperature range, τ_bulk evolution seems to depend on the wafer type (supplier and initial quality), probably due to the combined occurrence of concurrent bulk improvement and contamination mechanisms. Best pre-annealing conditions of tested as-cut Cz wafers significantly improve the wafer carrier lifetime and thus the cell efficiency up to +0.8%_abs. Nonetheless, further work is needed to foster our comprehension of the mechanisms responsible for the change in τ_bulk. Results suggest that behind well-known POCl₃ gettering route, low temperature gettering mechanisms might be further investigated in order to setup robust process applicable to the wafers of SHJ mass production.

This study initially employs Cs₀.₀₅FA₀.₈₁MA₀.₁₄PbI₂.₈₆Cl₀.₁₄ as the active layer for perovskite solar cells and explores the impact of using different concentrations of natural Centella asiatica (CICA) extracts mixed with chlorobenzene (CB) as anti-solvent in the one-step method of perovskite film preparation. Centella asiatica is rich in natural antioxidants and asiatic acid. It contains many hydroxyl ions, which are capable of capturing uncoordinated heavy metal Pb atoms. We found that devices made with 15% Centella asiatica extract mixed with CB achieved the highest power conversion efficiency (PCE), increasing from 14.3% to 18.5%. Moreover, the devices maintained 85% of their initial efficiency after being stored in a glove box for 25 days.