Research Background
Perovskite materials have become an ideal choice for next-generation photovoltaic materials due to their excellent optoelectronic properties and low-cost manufacturing processes. They are widely used in solar cells, photodetectors, and light-emitting devices. Compared to traditional silicon-based materials, perovskite materials offer significant advantages such as higher light absorption efficiency, broader spectral response, and lower processing costs. However, perovskite solar cells (PSCs), especially in the application of wide-bandgap perovskite (WBG) materials, still face many challenges, such as poor crystal quality, phase separation phenomena, and device stability issues, which severely restrict their efficiency and commercialization for large-area devices.
In this context, Professor Ke Weijun’s team from Wuhan University published a paper titled “Piracetam shapes wide-bandgap perovskite crystals for scalable perovskite tandems” in the journal Nature Nanotechnology. They designed and prepared a crystal modifier—piracetam—specifically to improve the crystal structure and optoelectronic properties of wide-bandgap perovskites. The team significantly increased the grain size and crystallinity of the perovskite films using piracetam, resulting in excellent optoelectronic performance and successfully addressing common issues such as surface roughness and non-uniformity in large-area devices.
Through the modulation of piracetam, the researchers not only promoted the preferential (110) crystal orientation of wide-bandgap perovskites but also formed one-dimensional (Pi) PbI2 nanoneedles at the grain boundaries through reactions with PbI3 perovskite, further reducing defects and improving the optoelectronic uniformity and stability of the films. Ultimately, the research team successfully achieved high power conversion efficiency (PCE) for large-area all-perovskite tandem solar cells (TSCs). They achieved PCEs of 28.71% (certified 28.13%) and 28.20% (certified 27.30%) for small (0.07 cm²) and large (1.02 cm²) area devices, respectively, with a PCE loss of only 0.51% between small and large area devices.
Research Highlights
(1) The experiment introduced the crystal modifier piracetam for the first time to regulate the nucleation process of wide-bandgap perovskites, resulting in large grain sizes, preferential (110) orientation, and uniform optoelectronic properties.
(2) The experiment formed one-dimensional (Pi) PbI2 nanoneedles at the grain boundaries through the reaction of piracetam with PbI3 significantly enhancing the crystallinity of the perovskite, reducing defects, and improving the smoothness of the grain surfaces.
(3) By modulating the grain growth and optoelectronic properties of WBG perovskites, the experiment successfully improved the performance and reproducibility of large-area all-perovskite tandem solar cells (TSCs), achieving PCEs of 28.71% (certified 28.13%) and 28.20% (certified 27.30%) for areas of 0.07 cm² and 1.02 cm², respectively.
(4) The experiment achieved high energy conversion efficiency for large-area TSCs by optimizing the homogenization process of WBG perovskites, demonstrating the broad applicability of this method across different perovskite compositions, increasing the PCE from 23.56% to 25.71% for single-junction solar cells with a 1.56 eV bandgap.
Illustrative Interpretation
Figure 1: Schematic diagram of the effect of piracetam on wide-bandgap perovskites.
Figure 2: The impact of piracetam on the crystal structure of wide-bandgap perovskite films.
Figure 3: The effect of piracetam on all-perovskite tandem solar cells.
Figure 4: Performance of 2T all-perovskite tandem solar cells.
Conclusion and Outlook
In summary, this paper demonstrates the effectiveness of piracetam as a crystal modifier, achieving high-quality wide-bandgap (WBG) films with preferential orientation, reduced defects, improved crystallinity, and ultra-smooth surfaces, further forming one-dimensional (Pi) PbI3 perovskites to enhance device performance. This method significantly reduces the open-circuit voltage (Voc) loss and greatly improves the power conversion efficiency (PCE) of WBG perovskite solar cells (PSCs) and all-perovskite tandem solar cells (TSCs).
Notably, the introduction of piracetam minimized the efficiency gap between small and large area tandem devices, achieving PCEs of 28.71% (certified 28.13%) and 28.20% (certified 27.30%) for 2T all-perovskite TSCs in aperture areas of 0.07 cm² and 1.02 cm², respectively. Despite these advancements, challenges remain for large-area tandem modules, particularly regarding phase separation and ion migration. Further progress requires the adoption of Br-reduced WBG sub-cells, NBG sub-cells without PEDOT:PSS, robust tunneling layers, and scalable deposition techniques, combined with advanced interface engineering strategies to drive the continued development of all-perovskite tandem technology.
Original Article Details:
Fu, S., Zhou, S., Meng, W. et al. Piracetam shapes wide-bandgap perovskite crystals for scalable perovskite tandems. Nat. Nanotechnol. (2025).
https://doi.org/10.1038/s41565-025-01899-z
Academic QQ Group for Nanomaterials
（To join the group: Please note: Name – Institution – Research Direction (without notes, please do not apply), approved by the administrator to join the group.)
One-dimensional Materials Group-1: 463352826
Two-dimensional Materials Group-2: 1075914107
Composite Materials Group-2: 834770793
Wearable Devices Academic Group: 1032109706
Photocatalysis Group-2: 927909706
Battery Discussion Group-1: 418038617