Smoothing out the surfaces of wide-bandgap perovskite solar cells

Wide-bandgap perovskite solar cells (WBG-PSCs) have rapidly emerged as valuable components in high-efficiency tandem photovoltaics. They include a tunable bandgap for optimized spectral utilization, they allow for increased voltage and absorption of high-energy photons, and they are generally cheaper to fabricate than traditional silicon solar cells. A recurring challenge, however, is presented by their intrinsically imperfect surfaces, which are caused by lattice strain and phase separation. This ultimately leads to residual stress, voltage loss, and operational instability.

To address this issue, Du et al. introduced a surface passivating crystalline — 1,3-diaminopropane dihydroiodide (PDADI) — into the fabrication process, helping reduce surface defect density and improve overall WBG-PSC performance.

“We adopted the use of PDADI to simultaneously ease lattice strain and inhibit phase separation,” said author Zhiyong Liu. “In simple terms, the addition … plays a ‘dual-function’ role. First, it stabilizes the crystal structure and reduces local strain. Second, it inhibits ion migration, thereby reducing the formation of inactive phases. This collaborative mechanism not only reduces defect density but also significantly enhances the carrier transport and lifetime of the WBG-PSC.”

The researchers employed various microscopy techniques to examine interfacial interactions between PDADI and the surface of perovskite films and to study the impact of including PDADI on film morphology. The cells they produced were shown to have superior power conversion efficiency (PCE) and environmental stability, maintaining more than 90% of their original PCE after 1,500 hours of operation.

“In the future, we’ll continue developing more stable and efficient WBG-PSC systems,” said Liu. “We want to further explore the texture structure of the silicon substrate integrated technology to help provide a practical foundation that promotes mass production.”

Source: “Lattice strain conversion suppresses ion migration to stabilize wide-bandgap perovskite solar cells,” by Yaru Du, Shanshan Du, Xiaobo Zhang, Hao Wang, Niqian Du, Xiaoyi Hou, Kaikai Liu, and Zhiyong Liu, Applied Physics Letters (2026). The article can be accessed at https://doi.org/10.1063/5.0311771 .