Progress in Photovoltaics最新文献

This study investigated the thermomechanical stress induced by annealing plated Cu contacts on pyramidal surfaces of Si heterojunction (SHJ) solar cells. The homogeneity of cell temperature during annealing was assessed by both experiment and simulation. Several influential factors on the Si stress were evaluated, including Cu geometries, contact edge locations, contact width, pyramid size, and annealing temperature. The simulated stress, which was verified by Raman spectroscopy, was applied to predict the probability of fracture in combination with the Weibull diagram obtained from four-point flexural (4PF) tests. Despite the identification of limiting flaw populations at the Si surface of Cu-plated SHJ cells, a low fracture probability was estimated for a typical annealing temperature of 200°C.

With the increasingly large volumes of silicon solar panels being decommissioned worldwide, we urgently need to come up with a cheap and efficient recycling strategy that yields high-value output materials. A crucial step in such recycling is to delaminate the front and back sheets to access the cells and their metallization. In this work, we demonstrate that the adhesion between the encapsulant and the silicon wafers can be weakened, in a fast and effective way, using a picosecond pulsed near-infrared laser. The glass and encapsulant are then delaminated from the silicon wafer in a thermomechanical step. This method provides direct access to the silicon emitter and bulk as well as the precious and/or toxic metals on its surface, enabling their recycling. Ablation threshold experiments show that the IR laser mostly interacts with the silicon, thereby indirectly ablating the SiN_x anti-reflective coating. We show that laser pattern and laser setting optimization help strike a balance between effective silicon wafer surface ablation and minimal (submicron thick) contamination from the encapsulant, due to lower heat dissipation into the wafer and encapsulant. The SiN_x removal, combined with high potential throughput and low OpEx, sets this process apart from existing delamination techniques. The process described in this paper can be crucial to enable rapid and energy-efficient recycling of silicon PV modules to high-purity raw materials with a high recovery rate.

A double halide-based perovskite photovoltaic cell has drawn considerable attention because of its lower toxicity supporting sustainable development goals (SDGs) in terms of a clean and healthy environment for nature, tunable bandgap, versatile structure, and improved stability. This study investigates the performance analysis of two nontoxic Pb-free environmentally friendly double perovskite solar cell (DPSC) materials, Cs₂AgBiI₆ and Cs₂AgBiBr₆ within a tandem solar cell (TSC) configuration. This research is focused on optimization and improving efficiency in Cs₂BiAgI₆-DPSC (top cell-1) and Cs₂AgBiBr₆-DPSC (top cell-2) using mathematical analysis. A modified filtered solar spectrum was employed to evaluate the bottom cell performance for real-time precision. These enhancements have led to outstanding results in the efficiency of power conversion (PCE) of 29.15% and 37.17% for the Cs₂AgBiI₆-based tandem cell and Cs₂AgBiBr₆-based tandem cell respectively. Furthermore, these two tandem cells are optimized using a variety of electron transporting layers (ETLs) and hole transporting layers (HTLs) to analyze the enhanced top cell. This is done step by step starting from finding out the strained spectrum and matching the current density for both the multi-junction cells. Both cells are also analyzed for different parameters such as defect density along with absorber width variation, intermediate defect density (IDD) and working temperature variation. Moreover, the outcomes with V_oc of 1.61 V, J_sc of 23.38 mA·cm⁻², FF of 77.57% and PCE of 29.15% for tandem cell-1 and V_oc of 2.08 V, J_sc of 21.85 mA·cm⁻², FF of 81.92%, and PCE of 37.17% for tandem cell-2 give conceptual insights for improving the efficiency of cesium-based photovoltaic solar cells (PVSC) and support the broader acceptance of environmentally pleasant and stable perovskites.

Perovskite solar cells often exhibit performance variability even under identical experimental conditions. One of the reasons of this inconsistency is attributed to manual interventions such as the application of antisolvents. To address these challenges, we develop an automated system to precisely control the solvent dropping and substrate heating processes. Spin-coating is performed by using an automated system comprising a robot arm, spin coater, automatic solution dropping part, hot plate, and substrate storage area. Manual fabrication is conducted simultaneously to compare the outcomes. The reproducibility of devices fabricated by using the system and intrabatch and interbatch consistency are assessed. The automated system considerably diminishes performance fluctuations across batches conducted on different dates. Especially, the automated, uniform application of an antisolvent considerably minimizes surface roughness variability in perovskite films. X-ray diffraction analyses further reveal differences between the residual PbI₂ contents of perovskite films fabricated via automated and manual methods. Additionally, grazing incidence wide-angle X-ray scattering measurements indicate that the residual PbI₂ depth distribution in the perovskite layer was influenced by the antisolvent drop rate and timing. The results suggest that precise control of antisolvent drop rates and drop timings can improve the reproducibility of perovskite solar cells.

Transition metal oxides (TMOs) such as MoO_x, featuring a high work function and a wide optical bandgap, are competitive alternatives to p-type a-Si:H or nano crystalline silicon in silicon heterojunction solar cells to form silicon compound heterojunction (SCH) solar cells. However, the thermal instability of MoO_x during the curing process of screen-printing restrains its massive production in industry. In this work, silver grids are printed on the MoO_x side of MoO_x SCH solar cells, and the influence of annealing atmosphere and temperature on the performance of the solar cells is investigated. After annealing in O₂ or air, the device performance is significantly degraded, while it remains almost unchanged after annealing in N₂ at 136°C. A conversion efficiency of 22.40% is achieved on the SCH solar cells with screen-printed Ag grids when annealed at 136°C for 40 min in N₂ atmosphere, which is equivalent to that of the solar cells with thermally evaporated grids. To reveal the annealing effect, systematic research is conducted on changes in optoelectronic property, contact resistivity, and compositional distribution of MoO_x, brought about by annealing in N₂, O₂, and air at different temperatures. Oxygen vacancies and conductivity both increase after annealing in N₂, contributing to more efficient hole carrier collection through defect state-assisted band-to-band transition. However, dipoles formed at the c-Si/MoO_x interface during N₂ annealing, proposed according to the calculation of differential charge density, might hinder the hole transportation from c-Si to MoO_x. A 1-nm Al₂O₃ layer inserted between a-Si:H(i) and MoO_x is found to be effective for mitigating the V_oc drop after annealing in air. The approaches exhibit great potential for implementing screen-printing on MoO_x SCH solar cells, rendering industrial production of MoO_x SCH solar cells feasible.