Solar Energy Materials and Solar Cells最新文献

Hydrogen (H) passivation is one of ideal candidates to reduce interfacial and bulk defects for providing good passivation by the light soaking process. Herein, we investigate the influence of the medium-temperature light soaking process on the passivation and electronic performance of the N-TOPCon solar cells. The medium-temperature light soaking process had the significant impact on the metallization-induced recombination of the p⁺⁺ layer and the Si substrate with a corroded silver (Ag) at a depth of >165 nm. During the light soaking process, the breaking the bending of (Si:H₂)_n bonds causes H transitions from a bound state in the Si–H bond to a free state. In this state, H captures movable Ag and boron atoms on the wafer's surface for passivation. The mechanism for enhancing the passivation on the metallization-induced recombination under the metal contact (J₀,_metal) of SiO_x/n⁺-poly-Si layer, the emitter dark saturation current density under the passivation layer (J₀) of p⁺ layer, and SiO_x/n⁺-poly-Si layer is to prevent the formation of new defects by removing excess H. An efficiency gain of 0.87 % was observed after the light soaking process, attributed to the increase in open circuit voltage (V_oc), short circuit current density (J_sc), and fill fact (FF) values by 10 mV, 0.15 mA/cm², and 1.5 %, respectively. The partial gain of FF comes from the effect of medium-temperature enhanced metal contact. This research contributes to a profound understanding of the mechanism behind improving the medium-temperature light soaking process improvement and offers a feasible strategy for enhancing the efficiency N-TOPCon solar cells. After optimizing the front surface recombination and the medium-temperature light soaking processes, we manufactured industrial-grade TOPCon cells with in-house efficiency (E_ff), V_oc, J_sc, and FF values as high as 25.8 %, 729 mV, 42.1 mA/cm², and 84 %, respectively.

Sn-doped indium oxide (ITO) film is one of the widely used transparent conductive oxide (TCO) materials. In recent years, reactive plasma deposition (RPD) technology has been used to prepare high-quality ITO film. Here, indium tin alloy is used to replace indium tin oxide as the evaporation source of RPD. By reacting with oxygen, the ITO film with a conductivity of 3.40 × 10³ S cm⁻¹ and a mobility of 121.40 cm² V⁻¹ s⁻¹ is deposited. The high mobility is mainly due to the high film crystallization rate, high doping efficiency and low Sn doping concentration. The ITO films are used as transparent conducting electrodes in silicon heterojunction (SHJ) solar cells, and a conversion efficiency of 25.38 % is achieved. Compared with conventional ITO films prepared using oxide targets, reaction-deposited ITO films using indium tin alloy have lower cost and higher quality, it is more suitable for mass production.

Understanding the elemental composition and point defect properties is crucial for improving device performance in Chalcogenide thin film solar cells. The correlation between composition and defect characteristics of CuSbS₂ thin film sulfurized from metallic precursors was systematically investigated. Interestingly, it was found that CuSbS₂ polycrystalline thin film maintains an overall Cu-rich composition with a Cu/Sb ratio greater than 1, regardless of the initial precursor compositions. Besides, no obvious difference in the performance of integrated devices is observed, due to the similar Cu/Sb atomic ratios and electronic properties (carrier concentration and mobility) in these CuSbS₂ thin films. By conducting admittance spectroscopy analysis on CuSbS₂ devices, identical defect energy was obtained at 280 meV above the valence band maximum, which can be ascribed to Cu_Sb. This could be mainly explained by the Cu-rich composition induced low formation energy of Cu_Sb. Therefore, further defects engineering focusing on Cu_Sb is required to boost the device efficiency of CuSbS₂ solar cells.

In various types of organic/inorganic solar cells, optical response enhancement is consistently observed within the external quantum efficiency spectra owing to the improvement in interface passivation and the suppression of carrier recombination. In this study, we focused on crystalline silicon solar cells and systematically investigated the impact of interface recombination on the optical response upon dual-side illumination using numerical simulations. The results shed light on the interesting phenomenon that the surface recombination velocity has a significant impact on the external quantum efficiency, and it changes as the illumination direction changes. Moreover, from a practical perspective, the spectra of external quantum efficiency under dual-side illumination conditions can act as a powerful tool for the quick diagnosis of the passivation quality at the top and bottom interfaces.

Lightweight modules are essential for next-generation vehicle-integrated photovoltaic (VIPV) applications, such as solar-powered cars, allowing integration of solar cells beyond the roof, and on the hood, boot and body panels, and thereby extending the driving range. However, the lightweight module's reliability and corresponding degradation mechanisms under various environmental stresses are less researched. In this work, we investigate interconnection and encapsulation strategies to improve reliability against damp heat and mechanical impact. We fabricated lightweight mini modules, weighing around 3.45 kg/m², and conducted hail impact and damp heat tests. These tests result in different failures, such as cracks in the solar cell, module delamination, and microcracks in the backsheet. By carrying out failure mechanism analysis and altering the fiber reinforcement in backsheet and encapsulation materials, we can increase resilience to these failure modes, thus providing guidance for the design of lightweight PV modules for next-generation VIPV.

Solar energy has experienced a surge in utilization, primarily through the adoption of solar photovoltaic (PV) panels, tapping into its abundant renewable potential. Efficiently cooling the operational surfaces of these PV panels is paramount for optimizing their performance and extending their lifespan. Cooling not only boosts electrical efficiency but also mitigates cell degradation. Temperature plays a crucial role in panel efficiency, particularly when temperatures exceed 25 °C, highlighting the need for effective cooling methods. Previous research has struggled to optimize control without relying on traditional cooling mediums. One promising approach involves attaching thermoelectric coolers (TECs) to the rear of PV panels, effectively reducing surface temperatures. To evaluate the economic viability of this approach, a comparative analysis is conducted between conventional systems and PV-TEC hybrid systems. A mathematical model describing the cooling process of PV modules is formulated, and simulations are carried out using MATLAB and the SCIP (Solving Constrained Integer Programs) in OPTI toolbox. The outcomes illustrate that precise control of TECs can increase the electrical output power efficiency of PV modules by 9.27 % while efficiently regulating surface temperatures. Furthermore, life cycle cost comparisons reveal that the hybrid system may be more cost-effective, boasting a 10.56 % cost saving over a 20-year project lifespan. A break-even point analysis indicates that the proposed system may break even in 6.5 years, demonstrating its potential for long-term economic benefits. This research underscores the significance of thermoelectric cooling in enhancing both performance and economic viability in solar PV systems.

Thermal management of photovoltaic (PV) panels is crucial due to the deterioration of their electrical efficiency at elevated operating temperatures. Therefore, thermal protection of PV against overheating is highly required. This study investigated the applicability of the shape-stabilized phase change material (PCM) composites for temperature regulation of PV modules (PVM). Paraffin waxes (PW) with specific melting temperatures infiltrate graphite foam (GF) to prepare the GF_PW composite. The PCM composites are coated with expanded graphite-modified epoxy resin to prevent PW leakage after melting and to maintain product stability, integrity, and mechanical strength. The performance improvement of PVMs integrated with two types of GF_PW composites with different phase change temperatures of 35 and 44 °C (labeled RT35 and RT44, respectively) was studied. The adequate latent heat and thermal conductivity of the epoxy-coated GF_PW composites ranged from 126.5 to 138.1 J/g and from 2.03 to 2.15 W/m°C, respectively. The GF_RT44 and GF_RT35 composites, used as passive heat absorbing elements, reduced the PVM surface temperature by 27 and 32 °C, respectively, enhancing the PVM efficiency by 10.9 and 18.5 % of the reference configuration consisting of the PVM alone. To our knowledge, the PVM efficiency enhancement obtained in this study is the highest among PVMs integrated with PCM composites reported in the literature.

In this work, an effective strategy for realizing high-performance silicon heterojunction (SHJ) solar cells involves replacing the existing rear single intrinsic hydrogenated amorphous silicon (i-a-Si:H) layer by depositing a bi-layer i-a-Si:H stack on the rear side using two different deposition chambers and manipulating the deposition temperature to inhibit epitaxial growth at the interface and maintain a good interfacial passivation effect. A low-temperature procedure is implemented to deposit the first anti-epitaxial i-a-Si:H buffer layer (I1 layer) of ∼1.5 nm thickness with a high hydrogen concentration and a low refractive index prior to the second bulk i-a-Si:H layer (I2 layer) of ∼5.5 nm thickness. The effects of the growth temperature and ignition power during deposition on the optical and structural properties of the i-a-Si:H buffer layers are investigated, and the impact of the buffer layers on carrier transport and collection is also evaluated. Utilizing this strategy, a trade-off between guaranteed passivation capability and low contact resistivity results in an improvement of 0.21%_abs in power conversion efficiency (PCE), which is mainly driven by increases in V_oc and FF, and a certified PCE of 25.92 %, with a high open circuit voltage (V_oc) of 749.7 mV, is achieved on a full-area M6-size industry-grade silicon wafer.

Rare-Earth oxyhydrides (REH_3-2xO_x) are characterized by photodarkening when illuminated by photons having an energy exceeding that of the band gap. We propose that the film is segregated in hydrogen rich and hydrogen poor areas. Upon illumination, the excited electrons reduce the three-valent cations inducing an insulator to metal transition in the hydrogen rich entities. These small metallic oxyhydride clusters are responsible for the enhanced optical absorption. In the surrounding semiconductor matrix the photoexcitation induces a transition from p to n-type conductivity. This persistent photoconductivity is due to trapping of the holes by hydride ions. As a result, the Fermi level rises above the conduction band inducing a Burstein-Moss effect and a large increase in the conductivity.