Key Takeaways & Executive Findings
- •• Two pre-crystallization processes, gas quenching and vacuum quenching, lead to different crystallization dynamics within perovskite thin films, affecting additive distribution. • A tailor-designed additive, 1,3-bis(4-methoxyphenyl)thiourea, improves the buried interface, achieving a certified efficiency of 23.75% for blade-coated perovskite solar cells. • The perovskite solar module (aperture area: 60.84 cm2) demonstrates an efficiency of 20.18% with excellent operational stability (T90 > 1000 h under maximum power point tracking). • The work provides insights into crystallization dynamics and additive engineering for scalable fabrication of efficient and stable perovskite photovoltaics.
Abstract
Gas quenching and vacuum quenching process are widely applied to accelerate solvent volatilization to induce nucleation of perovskites in blade-coating method. In this work, we found these two pre-crystallization processes lead to different order of crystallization dynamics within the perovskite thin film, resulting in the differences of additive distribution. We then tailor-designed an additive molecule named 1,3-bis(4-methoxyphenyl)thiourea to obtain films with fewer defects and holes at the buried interface, and prepared perovskite solar cells with a certified efficiency of 23.75%. Furthermore, this work also demonstrates an efficiency of 20.18% for the large-area perovskite solar module (PSM) with an aperture area of 60.84 cm2. The PSM possesses remarkable continuous operation stability for maximum power point tracking of T90 > 1000 h in ambient air.
1. Introduction
The efficiency of perovskite solar cells (PSCs) has continued to grow rapidly, as the small-area laboratory PSCs manufactured by the solution method have gained the certified power conversion efficiency (PCE) up to 26.7% [1]. The challenge to achieve high-quality perovskite thin films via solution method can be associated to the nucleation process that taken place within seconds and overlap each other, making the dynamics control needs to be strict, especially for the large-area perovskite thin film [2–4]. In general, rapid nucleation for pre-crystallization followed with slow crystal growth is necessary to form high-quality perovskites with fully surface coverage and large grain size [5, 6]. Anti-solvent extraction provides a picky strategy to obtain a perfect intermediate phase in spin-coating process that provides seed crystals for the growth of compact polycrystalline thin film with low bulk defects [7–9]. The anti-solvent method is not conducive to triggering uniform nucleation on perovskite surfaces with an area greater than 50 cm2, and it is difficult to obtain smooth perovskite films with high surface coverage [10–14].
Similarly, in the blade coating, gas quenching (GQ) and/or vacuum quenching (VQ) process are applied to accelerate solvent volatilization [15–18]. However, the concentration of wet film is relatively low before the quenching carried out, resulting in the solvent volatilization and reaching the minimum concentration for nucleation will take more times than the anti-solvent method. Ternes et al. obtained supersaturation rates of common quenching methods at critical concentrations by modeling, yielding ~102 s−1 for anti-solvent quenching, ~10−3−10−1 s−1 for VQ, and ~10−5−100 s−1 for GQ [19]. Low nucleation rate leads to inferior crystal, and this may be the reason why the efficiency of blade-coated PSCs still far leg behind the spin-coated counterparts.
The inference above prompted us to investigate the difference between GQ and VQ processes, because the different extraction processes seriously affect the crystallization dynamics, which is the key factor to determine the as-prepared film quality. For GQ, it is simple and economical, the supersaturation is relatively light, and the intermediate phase processing window is long [20–22]. For VQ, it can effectively achieve rapid nucleation to supersaturation, but with the increase in the film area, it has higher requirements for the vacuum system [19, 23, 24]. From the perspective of industrialization, GQ can be easily integrated in a production line and can be better combined with some in situ technologies to real-time monitoring, such as in situ X-ray diffractometer, in situ grazing incidence wide-angle X-ray scattering, and in situ photoluminescence. It is more in line with the demand of perovskite industrialization of cheap photovoltaic technology in principle [19, 20, 22, 25]. In addition, additive is a simple but effective strategy to optimize the intermediate phase through the formation of Lewis acid–base adduct or act as the sacrificial agent to ass
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Mengen Ma, Cuiling Zhang, Yujiao Ma, Weile Li, Yao Wang, Shaohang Wu, Chong Liu, Yaohua Mai (2024). Efficient and Stable Perovskite Solar Cells and Modules Enabled by Tailoring Additive Distribution According to the Film Growth Dynamics. Nano-Micro Letters. https://doi.org/10.1007/s40820-024-01538-7
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Frequently Asked Questions
What is the main finding of this study?
The study reveals that gas quenching and vacuum quenching lead to different crystallization dynamics in perovskite films, affecting additive distribution. A tailor-designed additive improves the buried interface, achieving high efficiency and stability in blade-coated perovskite solar cells and modules.
What efficiency was achieved for the perovskite solar cells?
The blade-coated perovskite solar cells achieved a certified efficiency of 23.75%.
What is the performance of the large-area perovskite solar module?
The perovskite solar module with an aperture area of 60.84 cm2 demonstrated an efficiency of 20.18% and excellent operational stability with T90 > 1000 hours under maximum power point tracking.
What additive was used and how does it work?
The additive is 1,3-bis(4-methoxyphenyl)thiourea. It is tailor-designed to improve the buried interface, reducing defects and holes, thereby enhancing device performance.
Why is this study significant for perovskite industrialization?
The study provides insights into crystallization dynamics and additive engineering for scalable blade-coating methods, which are more compatible with industrial production, potentially enabling cost-effective and stable perovskite photovoltaics.
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