Chang Yan

Perovskite solar cells (PSCs) have been considered as a next-generation disruptive photovoltaic technology, yet their advancement is constrained by the complexity of perovskite recipe with high-dimensional material and process design space. Despite the impressive general reasoning of Large Language Models (LLMs), they struggle with two limitations for application in PSCs: an inability to align general semantics with the perovskite domain knowledge, and an inefficiency in navigating high-dimensional perovskite material and recipe design spaces. To address these limitations, we introduce a domain-knowledge-guided framework PVK-LLM, a specialized model to serve as an expert to bridge general semantics with perovskite domain knowledge. By integrating this domain knowledge into a hierarchical Bayesian Optimization workflow, our approach efficiently navigates the high-dimension design space on a solar cell simulator platform. The domain knowledge resolves cold-start problems while dynamically adapting to simulator feedback. Moreover, in an individual wet-lab experiment aimed at maximizing power conversion efficiency (PCE), our framework autonomously proposes a novel synergistic four-component recipe comprising specialized organic passivation recipe (3MTPAI, PDAI2, EDAI2, and PipDI) which has not been reported in existing literature. This AI-designed recipe effectively achieves a champion PCE value of over 26.0 %, approaching world records achieved through extensive expert trial-and-error. Our approach can effectively enable LLM comprehend the domain knowledge, which can efficiently navigate in a high-dimensional, capable to accelerate the advancement in real-world perovskite as well as other material science development.

Ambient-air blade-coated perovskite solar cells achieve stable efficiency via synergistic passivation and carrier transport control.

Sulfide chalcopyrite copper indium gallium sulfide (CIGS₂) solar cells show great potential as the top cell candidate for the tandem configuration due to their tunable wide band gap (1.6–2.4 eV), high‐efficiency potential, and excellent stability. However, the preparation of high‐quality sulfide chalcopyrite CIGS₂ presents a significant challenge, primarily due to the lack of atmospheric control in sulfurization reactions. In this study, based on the sol‐gel method, a novel approach is proposed utilizing double‐zone temperature sulfurization to control the sulfur atmosphere and sample temperature independently. With this strategy, the optimized sulfurization condition manages better crystallization and a lower defect density for the CIGS₂ absorber layer. Simultaneously, NaInS₂ is found to be synthesized on the upper surface of the CIGS₂, enabling a better band alignment between CIGS₂ and the CdS buffer layer with less interfacial recombination. To further alleviate the mismatch of band alignment between the wide‐bandgap CIGS₂ absorber and buffer layer, an environmentally benign and more compatible ZnSnO (ZTO) buffer layer is utilized. As a result, an efficiency of 12.3% is attained for solution‐based wide bandgap CIGS₂ solar cells.

Thin-film solar cells, due to their low material usage and flexible substrates compatibility, have the potential to fill market niches for photovoltaic (PV) technologies. Among them, the Cu(In,Ga)Se₂ (CIGS) solar cell is a widely deployed mature technology. However, the usage of scarce material like Ga and In is considered a major hindrance for its further scaling up. The commercial opportunity of its promising counterpart Cu₂ZnSnS₄ (CZTS) with a similar structure but low-cost potential, has not yet been fully recognized. In this paper, the bottom-up approach is used to build models of cost analysis for CZTS on the different substrates with their probability distribution simulated by the Monte Carlo method. The resulting production costs are $41–52 per m², making them economically attractive. Prospective strategies for further cost reduction are also suggested. The fundamental technical features of CZTS are reviewed, identifying the large efficiency potential of this PV technology. Analysis of different market opportunities is performed to fit the market demands better. Moreover, possible constraints and promising pathways towards the commercialization of the emerging CZTS technology are proposed.

Graphene/silicon (Gr/Si) Schottky barrier solar cells (SBSCs) are attractive for harvesting solar energy and have been gaining grounds for its low-cost solution-processing. The interfacial barrier between graphene and silicon facilitates the reducing excessive carrier recombination while accelerating the separation processes of photo-generated carriers at the interface, which empowers the performance of Gr/Si SBSCs. However, the difficulty to control the interface thickness prevents its application. Here, we introduce the graphene oxide quantum dots (GOQDs) as a unique interfacial modulation species with tunable thickness by controlling the GOQDs particle size. The power conversion efficiency (PCE) of 13.67% for Gr/Si-based SBSC with outstanding stability in the air is obtained with the optimal barrier thickness (26 nm) and particle size (4.15 nm) of GOQDs. The GOQDs in Gr/Si-based SBSCs provide the extra band bending which further enhances the PCE for its photovoltaic applications.

The presence of ZnS precipitates is common in Cu₂ZnSnS₄ (CZTS) films due to the preferred Cu‐poor and Zn‐rich composition for high‐efficiency CZTS devices. It is important to identify their distribution in the film as it can serve as a fingerprint for the CZTS forming process. However, limited methods are viable to quantify their distribution as they are small in size and few in number. Herein, a fast and cost‐effective chemical treatment is presented that can reveal the nanoscale ZnS domains within CZTS films to be captured under a common scanning electron microscope (SEM). This method exploits a hole‐injection process driven by gold catalysis and the band alignment between CZTS and ZnS. ZnS precipitates as small as 10 nm in diameter can be revealed clearly. Using this approach, a characteristic lognormal size distribution of the ZnS precipitates close to the CZTS film surface with a median diameter of 80 nm and a density of around 2 in a 1 μm² surface area is demonstrated. Energy‐dispersive X‐ray spectroscopy (EDS) mapping and scanning transmission electron microscopy (STEM) imaging further confirm the existence of ZnS precipitates in the film. This method provides a fast means for capturing fingerprints of ZnS precipitations in CZTS process.

The one-dimensional photovoltaic absorber material Sb2S3 requires crystal orientation engineering to enable efficient carrier transport. In this work, we adopted a vapor transport deposition (VTD) method to fabricate vertically aligned Sb2S3 on a CdS buffer layer. Our work shows that such a preferential vertical orientation arises from the sulfur deficit of the CdS surface which creates a beneficial bonding environment between exposed Cd2+ dangling bonds and S atoms in the Sb2S3 molecules. The CdS/VTD-Sb2S3 interface recombination is suppressed by such properly aligned ribbons at the interface. Compared with typical [120]-oriented Sb2S3 films deposited on CdS by rapid thermal evaporation (RTE) method, the VTD-Sb2S3 thin film is highly [211]- and [121]- oriented and the performance of the solar cell is increased considerably. Without using any hole transportation layer, a conversion efficiency of 4.73% is achieved with device structure of ITO/CdS/Sb2S3/Au. This work provides a potential way to acquire vertical aligned thin films on different buffer layers.