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Solar power is not only the fastest growing energy technology in recent history but also one of the cheapest energy sources and the most impactful in terms of reducing greenhouse gas emissions.

A team of engineers at Huazhong University of Science and Technology in China has designed, built and independently tested an all-perovskite tandem solar cell with record efficiency. Their paper is published in the journal Nature Communications.

Solar energy is a promising way of reducing our dependence on fossil-fuel-based energy resources to opt for cleaner energy forms. Over the years, solar cells that can harness this renewable energy have undergone significant progress.

A research team has pushed the boundaries of solar cell technology. On July 3, a new world record for perovskite solar cell performance set by Professor Xu's (University of Science and Technology of China [USTC]) team was announced with a certified stable efficiency of 26.7%. The work is published in the journal Progress in Photovoltaics: Research and Applications.

Existing perovskite solar cells, which are unable to utilize approximately 52% of total solar energy, have been improved upon by a Korean research team. The team has developed an innovative technology that maximizes near-infrared light capture performance while greatly improving power conversion efficiency. This greatly increases the possibility of commercializing next-generation solar cells and is expected to contribute to important technological advancements in the global solar cell market.

A team of engineers and materials scientists at King Abdullah University of Science and Technology, in Saudi Arabia, working with a colleague from Helmholtz-Zentrum Berlin für Materialien und Energie, in Germany, has developed a blade-coated perovskite/silicon solar cell that tests at 31.2% efficiency.

Publication date: December 2024

Source: Materials Today Energy, Volume 46

Author(s): Ziyang Xia, Wenbin Zhang, Cheng Chen, Linqin Wang, Mengde Zhai, Ming Cheng

An international team led by the University of Surrey with Imperial College London have identified a strategy to improve both the performance and stability for solar cells made out of the "miracle material" perovskite by mitigating a previously hidden degradation pathway.

Northwestern University scientists have developed a new protective coating that significantly extends the life of perovskite solar cells, making them more practical for applications outside the lab.

Publication date: 28 February 2025

Source: Journal of Power Sources, Volume 630

Author(s): Tamar Danielyan, Arevik Asatryan, Arsen Sahakyan, Hayk Khachatryan

A machine learning (ML)-driven autonomous framework is introduced for optimizing the fabrication conditions of air-processed perovskite solar cells (PSCs). By effectively exploring a complex multidimensional parameter space, the framework identifies optimal conditions for high-performance PSCs with limited trials. This work demonstrates the potential of autonomous methodologies in accelerating the devolvement of solution-processed semiconductors.

Abstract

Traditional optimization methods often face challenges in exploring complex process parameter spaces, which typically result in suboptimal local maxima. Here an autonomous framework driven by a machine learning (ML)-guided automated platform is introduced to optimize the fabrication conditions of additive- and passivation-free perovskite solar cells (PSCs) under ambient conditions. By effectively exploring a 6D parameter space, this method identifies five parameter sets achieving efficiencies above 23%, with a peak efficiency of 23.7% with limited experimental budgets. Feature importance analysis indicates that the rotation speeds during the first and second steps of perovskite processing are the most influential factors affecting device performance, thereby meriting prioritization in the optimization efforts. These results demonstrate the exceptional capability of the autonomous framework in addressing complex process parameter optimization challenges and its potential to advance perovskite photovoltaic technology. Beyond PSCs, this work provides a reliable and comprehensive strategy for optimizing solution-processed semiconductors and highlights the broader applications of autonomous methodologies in materials science.

A team of solar engineers at Huaqiao University, working with a pair of chemists from the City University of Hong Kong and another colleague from the Chinese Academy of Sciences, has developed an improved perovskite solar cell with 26.39% efficiency. In their study, published in Nature Communications, the group used a hole-selective interlayer that inhibits ion diffusion to improve the device's stability.

Publication date: January 2025

Source: Materials Today Communications, Volume 42

Author(s): Xinqi Ai, Feiping Lu

Publication date: January 2025

Source: Journal of Energy Chemistry, Volume 100

Author(s): Hongrui Sun, Sanlong Wang, Pengyang Wang, Yali Liu, Shanshan Qi, Biao Shi, Ying Zhao, Xiaodan Zhang

Publication date: 15 February 2025

Source: Journal of Power Sources, Volume 629

Author(s): Yanpeng Meng, Chengxi Zhang, Shengbo Gong, Qirun Hu, Yunyue Feng, Jun Dai

In this work, Cu(In_0.3Ga_0.7)₃S₅ is developed as a novel hole transport layer (HTL) for perovskite solar cells. Careful cation management of the HTL significantly enhances the interfacial defect properties and lead to a 3.5× improvement in the T₈₀ (the time to retain 80% of the initial efficiency) lifetime of the solar cell device compared to conventional NiO HTL-based devices.

Abstract

Copper-chalcogenide-based inorganic holetransport layers (HTLs) are widely studied in perovskite solar cells (PSCs) because of their favorable valence band maximum and their ability to passivate interfacial defects through Pb-S interactions. These compounds are shown to produce stable PSCs because of their high intrinsic stability. However, the density functional theory (DFT) calculations and X-ray photoelectron spectroscopy analysis presented here reveal that the presence of Cu in the HTL can weaken the interfacial Pb-S interactions and compromise the device stability. A clear inverse relationship is observed between the stability of perovskite film and the Cu-concentration in the HTL underneath. Therefore, to minimize the detrimental effect of Cu, this work explores Cu-deficient chalcopyrite compounds, CuIn₃S₅ and Cu(In_xGa_(1-x))₃S₅, as HTLs for PSCs, which results in improved device stability. DFT calculations reveal that incorporating gallium into the HTL reduces the HTL-perovskite interfacial energy, which results in further enhancement of device stability. The average T₈₀ lifetimes (the time to retain 80% of the initial efficiency) under ambient conditions for the NiO, CuIn₃S₅, and Cu(In_0.3Ga_0.7)₃S₅ HTL-based devices are 200, 449, and 656 h, respectively. These findings underscore the significant roles of cations and anions of the inorganic transport layer in enhancing the stability of the PSCs.

Publication date: 15 February 2025

Source: Journal of Power Sources, Volume 629

Author(s): Babneet Kaur, Debanjan Maity, Partha Ghosal, Melepurath Deepa

Achieving multifunctional encapsulation is critical to enabling perovskite solar cells (PSCs) to withstand multiple factors in real-world environments, including moisture, UV irradiation, hailstorms, etc. This work develops a two-step and economical encapsulation strategy with shellac to protect PSCs under various accelerated degradation experiments. This strategy not only enables PSCs to pass outdoor stability, UV preconditioning, and hail tests according to the International Electrotechnical Commission 61215 standard (IEC61215) but also significantly reduces lead leakage. This simple, cost-effective, and multifunctional encapsulation strategy increases the commercial prospects of perovskite solar cells.

Publication date: April 2024

Source: Journal of Energy Chemistry, Volume 91

Author(s): Haikuo Guo, Fuhua Hou, Xuli Ning, Xiaoqi Ren, Haoran Yang, Rui Liu, Tiantian Li, Chengjun Zhu, Ying Zhao, Wei Li, Xiaodan Zhang

In perovskite solar cells (PSCs), engineering the interface between perovskite absorber thin films and charge transport layers has been pivotal. Self-assembled monolayers (SAMs) in the electron-blocking layer have improved contact efficiency, reducing interfacial recombination. SAM growth models and plasma treatment for conformal SAM growth are investigated, suppressing non-radiative recombination. This approach achieves 24.5% power conversion efficiency (stabilized at 23.5%) in inverted PSCs.

Abstract

Significant advancements in perovskite solar cells (PSCs) have been driven by the engineering of the interface between perovskite absorbers and charge transport layers. Inverted PSCs offer substantial potential with their high power conversion efficiency (PCE) and enhanced compatibility for tandem solar cell applications. Conventional hole transport materials like poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and poly(triaryl amine) (PTAA) not only constrain the PSC efficiency but also elevate their fabrication costs. In the case of improving inverted structured PSCs according to the aforementioned concerns, utilizing self-assembled monolayers (SAMs) as hole-transporting layers has played a crucial role. However, the growth of self-assembled monolayers on the substrates still limits the performance and reproducibility of inverted structured PSCs. In this study, the authors delve into the growth model of SAMs on different surface morphologies. Moreover, it is found that the plasma treatment can effectively regulate the surface morphologies of substrates and achieve conformal growth of SAMs. This treatment improves the uniformity and suppresses non-radiative recombination at the interface, which leads to a PCE of 24.5% (stabilized at 23.5%) for inverted structured PSCs.

SPINBOT, a fully automated platform, integrates machine learning to optimize solution-processed perovskite thin films. It efficiently explores an intricate multi-dimensional parameter space to produce high-quality and reproducible films. As a result, the optimized film achieves an impressive 21.6% power conversion efficiency in solar cells under ambient conditions, along with excellent long-term stability.

Abstract

Simultaneously optimizing the processing parameters of functional thin films remains a challenge. The design and utilization of a fully automated platform called SPINBOT is presented for the engineering of solution-processed functional thin films. The SPINBOT is capable of performing experiments with high sampling variability through the unsupervised processing of hundreds of substrates with exceptional experimental control. Through the iterative optimization process enabled by the Bayesian optimization (BO) algorithm, the SPINBOT explores an intricate parameter space, continuously improving the quality and reproducibility of the produced thin films. This machine learning (ML)-guided reliable SPINBOT platform enables the acceleration of the optimization process of perovskite solar cells via a simple photoluminescence characterization of films. As a result, this study arrives at an optimal film that, when processed into a solar cell in an ambient atmosphere, immediately yields a champion power conversion efficiency (PCE) of 21.6% with satisfactory performance reproducibility. The unsealed devices retain 90% of their initial efficiency after 1100 h of continuous operation at 60–65 °C under metal-halide lamps. It is anticipated that the integration of robotic platforms with the intelligent algorithm will facilitate the widespread adoption of effective autonomous experimentation to address the evolving needs and constraints within the materials science research community.

Our innovative subsurface lattice reconstruction strategy enhances halide perovskite’s stability by favoring corner-sharing octahedra, reducing defects, and optimizing valence band alignment. FA0.92Cs0.08PbI3-based devices achieve a remarkable efficiency and stability. This work represents a significant advancement in developing highly efficient and stable perovskite materials for diverse applications, such as solar cells, light-emitting diodes, and lasers.

Perovskite Solar Cells

In article number 2203859, Nastaran Meftahi, Maciej Adam Surmiak, Andrew J. Christofferson, and co-workers present a methodology for efficiently exploring the vast compositional space of quasi-2D Ruddlesden-Popper perovskite solar cells using a combination of machine learning and a reproducible, combinatorial high-throughput robotic fabrication process. This methodology provides a platform for further optimization of solar cell power conversion efficiency and stability.

It is shown that using an enantiomerically pure chiral fullerene as the electron transport layer (ETL) in a perovskite solar cell (PSC) gives an enhanced power conversion efficiency and improved stability, over the racemic material. This provides strong evidence that single isomer ETLs can improve PSC performance and positions chiral fullerenes as an exciting material class moving forward.

Abstract

The rapidly advancing improvements in perovskite solar cells (PSCs) are driven, in part, by the inclusion of suitable electron transport layers (ETLs) in high performance devices. Fullerene derivatives are particularly useful ETLs in PSCs, but many of the utilized fullerenes are present as isomeric mixtures. The opportunities presented by single-isomer, single-enantiomer fullerenes in PSCs are poorly understood. Here, inverted PSCs are prepared using bis[60]phenyl-C61-butyric acid methyl ester derivative (anti)16,17-bis[60]PCBM, comparing the performance of enantiomerically pure material to the corresponding racemate. The single enantiomer devices are found to have an improved performance, giving a power conversion efficiency (PCE) of 23.2%, compared to 20.1% PCE for the racemate. It is also shown that enantiomerically pure PSC modules can be prepared with a state-of-the-art PCE of 20.1%. Such excellent performance for the single enantiomer devices is accompanied by enhanced operational stability. This study thus provides strong evidence that single isomer ETLs can provide important improvements in PSC performance and it positions chiral fullerenes as an exciting material class moving forward.

Ammonium salt is utilized in NiO as a relatively neutral stabilizer to improve the stability and hole transport capability of NiO. Inverted MAPbI₃-based perovskite solar cells based on this novel NiO exhibit high power conversion efficiency (PCE) of 19.91% with exceptionally a high V _oc of 1.13 V and excellent stability, maintaining 97% of its initial PCE after 800 h.

Abstract

Nickel oxide (NiO) is one of the promising hole-transporting materials for perovskite solar cells (PSCs). Despite the ongoing efforts to improve PSC performance with sol–gel NiO, there has been limited study on the usage and influences of stabilizers on NiO and the relevant performance of PSCs. Until now, most of the sol–gel NiO methods use chemical stabilizers based on strongly acidic or mild basic catalysts such as hydrochloric acid and monoethanolamine. However, it is evident that the remaining pH-biased stabilizers in the film aggravate device stability. Therefore, it is imperative to develop a more stable and effective NiO, which can boost the performance of PSC. Here, the relatively neutral ammonium salt is utilized in NiO solution, which can improve the hole transport capability and stability of NiO. Under the optimum salt condition, energy level and hole conductivity are modulated favorably for hole transportation. Moreover, constructive interaction between the ammonium salt and perovskite enhances interfacial properties and reduces trap-assisted recombination. Based on this novel NiO, the champion power conversion efficiency of 19.91% with an exceptionally high open-circuit voltage of 1.13 V among the reported MAPbI₃-based PSCs is demonstrated. Furthermore, NiO with salt stabilizer secures long-term device stability, maintaining 97% of initial power conversion efficiency (PCE) even after 800 h.