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Abstract:

AbstractSkin, the largest organ in the human body, is sensitive to external stimuli. In recent years, an increasing number of skin‐inspired electronics, including wearable electronics, implantable electronics, and electronic skin, have been developed because of their broad applications in healthcare and robotics. Physical sensors are one of the key building blocks of skin‐inspired electronics. Typical physical sensors include mechanical sensors, temperature sensors, humidity sensors, electrophysiological sensors, and so on. In this review, we systematically review the latest advances of skin‐inspired mechanical sensors, temperature sensors, and humidity sensors. The working mechanisms, key materials, device structures, and performance of various physical sensors are summarized and discussed in detail. Their applications in health monitoring, human disease diagnosis and treatment, and intelligent robots are reviewed. In addition, several novel properties of skin‐inspired physical sensors such as versatility, self‐healability, and implantability are introduced. Finally, the existing challenges and future perspectives of physical sensors for practical applications are discussed and proposed.image

Abstract:

Improving the bulk quality of perovskite films is critical for achieving higher-performance photovoltaic devices. Chloride-containing additives, including lead chloride (PbCl₂) and methylammonium chloride (MACl)—standard additives widely adopted in perovskite photovoltaics—are effective for controlling crystallisation kinetics and grain morphology. However, the distinct impacts of different forms of chloride additives on nanoscale phase uniformity and luminescence homogeneity remains underexplored. Here, we provide new insights into how the choice and combination of chloride additives influence phase transitions and spatially uniform carrier dynamics within perovskite films. We demonstrate that strategically combining MACl and PbCl2 improves crystallinity and optoelectronic uniformity across dimensions spanning micrometres to millimetres. Leveraging these findings, we fabricated inverted (p-i-n) perovskite solar cells achieving certified quasi-steady-state efficiencies of 26.4% and 24.5% at device areas of 0.05 and 1 cm², respectively. Furthermore, these devices exhibit robust operational stability, retaining 88% of their initial performance after 1200 hours of continuous maximum power point tracking at elevated temperatures (65 °C) under simulated AM1.5G illumination. Our results elucidate the mechanistic differences between chloride additive forms, providing a viable strategy for advancing large-area, high-efficiency, and thermally stable perovskite photovoltaics.

Abstract:

Metal halide perovskite-based tandem solar cells are promising for achieving power conversion efficiency beyond the theoretical limit of their single-junction counterparts. However, the mediocre absolute efficiency and poor operational lifetime of wide-bandgap perovskite solar cells remain major hurdles for realising efficient and stable perovskite tandem cells. These issues can be attributed to non-radiative losses, heterogeneous crystallisation of the mixed-ion perovskites required for wide-bandgap, and light-induced halide segregation.

In Chapter 4, we report a holistic approach to overcoming challenges in 1.8-eV perovskite solar cells by engineering the perovskite crystallisation pathway by means of chloride additives. In conjunction with employing a self-assembled monolayer as the hole transport layer, we achieved a VOC of 1.25 V and a ηMPPT of 17.0%. We elucidate the key role of methylammonium chloride addition in facilitating the growth of a chloride-rich intermediate phase that directs crystallisation of the desired cubic perovskite phase and induces more effective halide homogenization. The as-formed 1.8-eV perovskite demonstrates suppressed halide segregation and improved optoelectronic properties.

In Chapter 5, we demonstrate the first intermediate phase formed in co-evaporated 1.7-eV perovskites with a dimethylammonium iodide additive. The modified perovskite film achieved grain sizes of a few micrometers, which is around 5 times larger than the control film, implying the great promise of using intermediate phase-assisted crystallisation to control the morphology of co-evaporated perovskites. Nevertheless, the sublimation of dimethylammonium iodide contaminated the evaporation chamber, hence, alternative molecules are required.

Finally, in Chapter 6, we establish the correlations between the optoelectronic and crystallographic properties of evaporated and solution-processed 1.67-eV perovskites and their macroscopic device performance and operational longevity. Interestingly, the evaporated perovskites have high crystallinity, uniaxial orientation, horizontally and vertically homogeneous grains, as well as solvent-free nature, leading to exceptional intrinsic stability under heat and light. For the first time, we demonstrate an evaporated 1.67-eV perovskite solar cell with comparable efficiency and stability to the stateof-the-art solution-processed cells. Furthermore, we demonstrate a fullyevaporated perovskite-Si tandem solar cell on a 1 cm2 micro-textured Si wafer with a ηMPPT over 23%. We further show that our co-evaporated perovskiteSi tandem devices achieve excellent field-lifetime stability, maintaining 80% of their initial performance over eight months of continuous operation.

This thesis provides effective approaches to address the issues of widebandgap perovskites and an in-depth understanding of the underlying mechanisms that affect the performance and stability of solution-processed and evaporated wide-bandgap perovskite solar cells. This will help significantly in the successful advancement of efficient and stable perovskite tandem technologies in the future.