Pang Jinglin,Duan Tianpeng,Liao Min,Jiang Limei,Zhou Yichun,Yang Qiong,Liao Jiajia,Jiang Jie
As the core component of ferroelectric memories, HfO 2 -based ferroelectric thin films play a crucial role in achieving their excellent storage performance. Here, we improved the ferroelectric properties and domain switching properties through in situ stress loading during annealing. The thin films are annealed under different bending states by applying different stress actions, and it is observed that, within a certain range of stress bending, the optimization of the ferroelectric properties of the annealed thin films can reach an extreme value. Specifically, under the influence of a small electric field, the 2 P r values of thin films annealed at +10 and −10 mm increased by 87.1% and 71.1%, respectively, compared with the unbent films. Additionally, these thin films exhibit extremely high domain wall mobility and excellent domain switching capabilities. Once the ferroelectric phase is formed through in situ stress modulation, it remains stable even under multiple service environments.
Haochen Ye,Yucheng Liu,Yunxia Zhang,Zhuo Xu,Jiaxue You,Lili Gao,Bing Li,Zhou Yang,Bobo Zhang,Shengzhong Frank Liu
Halide-composition engineering has been recognized as an effective means to stabilize formamidine (FA)-based perovskite (FAPbI3) in thin-film devices. However, the influence of a halide mixture on the lattice strain, trap density, carrier lifetime, and phase stability remains unclear. Herein, FAPbBrxI3–x single crystals (SCs) are grown as a model to study how halide composition would affect the inner strain and the optoelectronic properties. It is found that by gradually increasing the Br/I ratio from 0:1 to 1:0, the inner strain can be regulated. X-ray diffraction results show excellent phase stability of FAPbBrxI3–x SCs (stable in an ambient atmosphere over 1.5 years when x ≥ 0.5) because of the released expansion stress in the cubic lattice. The relevant photodetector presents good performance with an on–off ratio exceeding 103, a dark current as low as 10–10 A, a linear dynamic range (LDR) of 111 dB, detectivity of 4 × 1011 Jones, and long-term photostability. The present work paves a path toward the design of high-quality devices based on composition-optimized FAPbBrxI3–x SCs with predictable optoelectronic properties.
Yang Ding,Erming Feng,Siyuan Lu,Jianhui Chang,Caoyu Long,Sichao Tong,Hengyue Li,Junliang Yang
Residual stresses generated within perovskite films during the high-temperature annealing and cooling process are the key contributors to the reduction of device performance and lifespan deterioration. Herein, a strategy of surface micro-etching and reconstruction is developed to regulate the stresses in a triple-cation (formamidine, methylamine, and cesium) perovskite film. A precise stoichiometric mixture of L-lactic acid (LA) and isopropanol (IPA) is used to controllably dissolve the surface of the perovskite film, followed by octylammonium iodide (OAI) post-treatment, enabling a sinking reconstruction of 2D perovskite from the surface to bulk phase and achieving a benign transition from surface tensile stress to compressive stress, as well as a more matchable interface energy level. As a result, the target perovskite solar cells (PSCs) yield an obviously enhanced power conversion efficiency (PCE) of 25.54%, which is the highest reported PCE for triple-cation PSCs. Meanwhile, PSC modules with 10.4 cm2 achieve a PCE of 21.02%. Furthermore, the surface micro-etched and reconstructed PSCs exhibit superior stability, and the PSC devices without encapsulation can maintain 83% of original efficiency after 500 hour illumination at maximum power point tracking (MPPT) in a N2 atmosphere. This study provides a valuable avenue to improve PSC stability and efficiency by regulating residual stresses through surface micro-etching and reconstruction.
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