Quasi-two-dimensional (quasi-2D) Ruddlesden-Popper (RP) perovskites with layered structures are promising photovoltaic materials owing to their improved environmental stability, but their power conversion efficiencies (PCEs) still lag behind those of state-of-the-art 3D perovskites. Here, we investigate the bromine-substitution position effect of aromatic spacers in quasi-2D RP perovskite solar cells by comparing the meta- and para-substituted spacer molecules m-BrPEAAA and p-BrPEAAA. We show that para substitution induces a larger molecular dipole, strengthens spacer-framework interaction, and promotes more ordered crystallization. As a result, the p-BrPEAAA-based quasi-2D RP perovskite film exhibits improved crystallinity, prolonged carrier lifetime, and more favorable electronic structure. The corresponding device achieves a champion PCE of 20.16%, outperforming its meta-substituted counterpart (18.91%). In addition, the para-substituted system shows improved thermal and moisture stability. This work highlights bromine substitution-position engineering as an effective strategy for regulating spacer-framework interaction and improving the efficiency and stability of quasi-2D RP perovskite solar cells.

Fully screen-printed perovskite solar cells represent a promising solution for scalable manufacturing of perovskite photovoltaics. However, their development is hindered by inefficient vertical phase transformation within thick, multi-layered films, which results in incomplete infiltration, premature surface nucleation and residual stress. Here we report a fluid motion crystallization strategy employing a co-solvent system of ionic liquid methylammonium propionate and butyronitrile. The butyronitrile reduces the fluid motion resistance and disperses PbI2 aggregates with optimized solvation structure, enabling rapid and deep infiltration of the perovskite precursor. This promotes a bottom-up, ordered phase transition before surface nucleation, effectively suppressing defect formation. The subsequent growth of a dense, interconnected perovskite nanocrystal network featuring an island-like surface morphology strengthens the interfacial contact with the carbon electrode. This intimate contact enhances the carrier transport and minimizes the recombination losses. Finally, air-processed, fully screen-printed perovskite solar cells yield a power conversion efficiency of 22.41% (certified 21.86%). Devices retain over 90.5% of their initial power conversion efficiency after 2,000 h under International Summit on Organic Photovoltaic Stability light-soaking-1 (ISOS-L-1) accelerated ageing conditions and show no degradation after 900 h of operation at 85 °C with 50% ± 10% relative humidity (ISOS-L-3 protocol). Solvent engineering optimizes fluid motion and crystallization in fully screen-printed perovskite solar cells, resulting in devices with a certified power conversion efficiency of 21.86%, 90.5% of which is maintained after 2,000 h of operation.

To overcome the theoretical efficiency limit of single-junction perovskite solar cells (PSCs), the development of all-perovskite tandem solar cells (APTSCs) has attracted significant interest due to their low cost, high efficiency, and compatibility with flexible substrates. Currently, the performance of APTSCs is primarily constrained by the inferior performance of narrow-bandgap lead-tin (Pb─Sn) perovskite sub-cells, stemming from poor interface quality caused by Sn2+ instability and an unbalanced crystallization process. Encouragingly, recent breakthroughs in rational interface engineering have enabled the construction of high-quality Pb─Sn perovskite films with optimized interfaces, boosting the efficiency of APTSCs beyond 30%. Herein, we provide a comprehensive review of the recent advances in interface engineering for realizing efficient Pb─Sn PSCs and APTSCs. First, we introduce the fundamental challenges and potential solutions associated with the different interfaces in Pb─Sn PSCs, including the grain boundaries, buried interface, and top interface. Subsequently, we carefully examine cutting-edge strategies and their underlying mechanisms for addressing these interface issues of Pb─Sn PSCs, and the corresponding performance of their APTSCs is also summarized. Finally, we offer a critical perspective on this exciting field. This review is intended to inspire new ideas for further performance improvements in Pb─Sn PSCs and APTSCs.

Non-contact temperature sensing technology based on fluorescence intensity ratio (FIR) relies on the change in FIR of two different emission bands with temperature in fluorescent materials. When both emission bands exhibit normal thermal quenching (TQ), the temperature measurement sensitivity is often limited. In recent years, the potential of anti-TQ in the field of temperature sensing has gradually been explored, offering new insights for improving this situation. In this work, a novel dual-emission phosphor Lu2SrAl4SiO12: Cr3+, Fe3+ was adopted for fluorescence temperature sensing in near infrared (NIR) spectral region. Under 430 nm excitation, the phosphor exhibits broadband NIR emission centered at 703 nm (Cr3+) and 820 nm (Fe3+), both falling within the first biological window. Notably, Cr3+ displays a distinct anti-TQ behavior in the 600–680 nm and 706–775 nm regions, accompanied by spectral broadening. In contrast, Fe3+ exhibits a typical TQ behavior. Based on this opposite temperature response, a novel FIR model was constructed by integrating the anti-TQ region and the TQ region. The maximum absolute (Sa) and relative (Sr) sensitivities reach 0.63% K−1 at 373 K and 0.87% K−1 at 298 K, respectively. These results suggest that the Lu2SrAl4SiO12: Cr3+, Fe3+ phosphor offers a viable approach for NIR temperature sensing in biological tissues.

The lack of reliable energy harvesting devices on power transmission lines is a major obstacle to the development of line condition monitoring systems. This study designs a triboelectric-electromagnetic hybrid wide-band vibration energy harvester for power transmission lines. By integrating a triboelectric nanogenerator (TENG) with an electromagnetic generator (EMG) through a well-designed structural configuration, this approach leverages the TENG's superior output and the EMG's high-frequency, high-efficiency response to enable vibration energy harvesting across a wide frequency range of 1-70 Hz. To address the performance limitations of the TENG dielectric layer, MXene/Ecoflex composite films with an oriented structure were prepared by an electric fieldassisted method. A PI film was introduced as a charge storage layer to suppress the bottom charge neutralization effect, achieving a 38% improvement in the TENG's output performance. By conducting tests on a vibration test platform, the composite device demonstrated excellent performance in harvesting vibration energy and powering small electronic devices. This study provides novel insights into the design of TENG dielectric layers and offers a reliable solution for designing vibration energy harvesting devices for power transmission lines.

The performance of all-perovskite tandem solar cells (APTSCs) has been limited by narrow-band-gap lead-tin (Pb-Sn) perovskite sub-cells because of the uncontrollable crystallization and poor interface quality of Pb-Sn films, and a feasible strategy to comprehensively address these problems remains elusive. Herein, a two-dimensional (2D) 2-phenylethane-1-aminium lead iodide (PEA2PbI4) single crystal is demonstrated to serve as a “three-in-one” interface modifier, functioning as crystallization controller, buried seed, and capping passivator, to fabricate high-quality Pb-Sn films. The interaction between PEA2PbI4 and Pb-Sn perovskite promotes homogeneous nucleation and vertical crystal growth while strengthening both interfaces of the Pb-Sn films, enabling efficient charge transport and extraction. This three-in-one agent delivers Pb-Sn perovskite solar cells with an efficiency of 24.07% and T90 (time when efficiency dropped to 90%) over 2,000 h under ISOS-L-1. The constructed two-terminal APTSCs achieved an efficiency of 30.07% (certified 29.22%) with a fill factor (FF) of 84.77% and T90 over 1,800 h under ISOS-L-1.

Inverted (p-i-n structure) perovskite solar cells (PSCs) have garnered substantial commercial interest owing to their superior operational stability, solution-processability, and inherent compatibility with tandem architectures. Recent achievements in performance rivaling that of regular (n-i-p structure) devices, coupled with significant progress in large-scale fabrication, have intensified research momentum in this field. Nevertheless, the still-constrained efficiency of inverted PSCs remains a critical challenge that requires fundamental understanding and resolution. Herein, we summarize recent advancements in inverted PSCs, delving into the origins of energy losses and their impact on device performance. We highlight effective strategies to enhance the high-performance capabilities of inverted PSCs, focusing on advances in charge transport layers, interface engineering and perovskite film modification. Furthermore, we critically evaluate the latest progress in scalable fabrication and long-term stability. Finally, we delineate key future research directions essential for achieving high efficiency, durability and manufacturability to ensure the commercial viability of this promising technology.

Amid the global imperative for energy transition, perovskite tandem photovoltaics have emerged as a promising strategy to transcend the Shockley-Queisser (S-Q) limit of single-junction solar cells, having witnessed remarkable advances in recent years. This review comprehensively examines the progress in two predominant tandem configurations, perovskite/silicon and all-perovskite architectures. Key breakthroughs have been achieved through the synergistic passivation of bulk and interface defects in wide-bandgap (WBG) perovskites, the design of efficient interconnection layers (ICLs), and the optimization of narrow-bandgap (NBG) subcells. As a result, two-terminal (2T) tandem solar cells (TSCs) have achieved significant breakthroughs in certified power conversion efficiencies (PCEs), with perovskite/silicon and all-perovskite architectures exceeding 34% and 30%, respectively, and demonstrating exceptional optoelectronic characteristics. Furthermore, advancements in large-area module fabrication, including homogeneous film deposition, defect suppression, and monolithic integration, have laid a strong foundation for scalable production. Despite the challenges related to long-term operational stability, large-area manufacturing uniformity, and cost-effective processing, the high efficiency potential and versatility of perovskite tandem technology are anticipated to play a pivotal role in future energy systems, driving the evolution of next-generation photovoltaics.

Wide-bandgap (WBG) perovskite solar cells (PSCs) have emerged as ideal top-cell candidates for multi-junction tandem solar cells (TSCs), and the easily tunable bandgap of WBG perovskites enables optimal spectral matching with various narrow-bandgap (NBG) bottom cells. However, bandgap widening through compositional mixing at the A- or X-site introduces critical challenges, including uncontrolled crystallization, phase instability, and energy-level misalignment with charge transport layers. These issues lead to severe open-circuit voltage loss and poor device stability. In recent years, numerous innovative strategies have been proposed to address these limitations, resulting in significant breakthroughs that have substantially boosted the performance of both WBG PSCs and TSCs. This review systematically summarizes the state-of-the-art progress in WBG PSCs and their pivotal role in advancing TSCs. We first outline the fundamental challenges inherent to two primary classes of WBG perovskites: mixed-halide (I/Br) and pure-iodide compositions. Subsequently, we comprehensively examine advanced strategies developed for fabricating efficient and stable WBG PSCs. Furthermore, we highlight the latest progress in integrating WBG PSCs into various multi-junction TSC architectures. Finally, we provide a perspective on the key future directions for WBG PSCs and their tandem applications. This review can provide key insights for the further development of perovskite-based multi-junction tandem photovoltaics.

Pb-Sn perovskite solar cells (PSCs) have attracted growing interest as ideal narrow-bandgap sub-cell in all-perovskite tandem solar cells (APTSCs). However, the strong Lewis acidity and metastable nature of Sn2+ leads to the poor quality of spontaneously crystallized Pb-Sn perovskite film. Although introducing dimethyl sulfoxide (DMSO) as coordination additive together with quenching techniques has been adopted to improve Pb-Sn film quality, DMSO-induced Sn2+ oxidation and the complexity of quenching techniques hinder their large-scale development, and thus a DMSO- and quenching-free route is highly expected. In this work, we developed a dual-interface management strategy to control the spontaneous crystallization by introducing ionic-liquid (MAAc) atmosphere at the top interface and two-dimensional perovskite (F-PEA2PbI4) at the bottom interface. The MAAc atmosphere retards nucleation and induces vertical growth of Pb-Sn crystals, while the F-PEA2PbI4 seeds provide uniform nucleation sites and enhance buried interface of Pb-Sn films. The produced Pb-Sn PSCs yield a champion efficiency of 22.06% with 20.86% efficiency on 1 cm2, which are the highest value for DMSO- and quenching-free Pb-Sn PSCs to-date. Unencapsulated device maintains 95% of its initial efficiency after 1600 h under ISOS-D-1 and 80% after 1300 h under ISOS-L-1 conditions. Moreover, a four-terminal APTSCs reaches an efficiency of 28.11%.

Developing narrow-bandgap Pb-Sn perovskite solar cells (PSCs) for all-perovskite tandem device has been a hotspot during the past few years. To maximize infrared light absorption, a sufficient thickness of the Pb-Sn perovskite film is required. However, this introduces problems with unbalanced crystallization and poor buried interfaces. Therefore, effective strategies are desired to precisely control the vertical growth of Pb-Sn crystals and improve the buried interface for efficient charge transport and extraction, in order to construct efficient Pb-Sn PSCs. Herein, an F-PEA2PbI3SCN 2D perovskite seed layer was developed to guide crystal growth and improve the buried interface of FA0.7MA0.3Pb0.5Sn0.5I3 perovskite film. The 2D perovskite seeds were found to eliminate the formation of the SnI2 phase and promote energy level alignment, which improved the buried interface. Additionally, the uniform distribution of 2D seeds facilitated crystallization and guided the vertical growth of Pb-Sn crystals, resulting in a film with reduced defect density and released residual strain. Therefore, the optimized PSCs yielded a champion PCE of 22.71% with a broadened antisolvent-processing window and robust stability. Notably, the four-terminal all-perovskite tandem device exhibited a PCE of 27.68% with a stable power output of 27.2%. This work presents a new avenue for fabricating efficient Pb-Sn PSCs by rationally controlling their crystallization behavior.

Tin (Sn)-based perovskites show significant potential in lead-free perovskite optoelectronics. Currently, the spin-coating method combining DMSO co-solvent and antisolvent-dropping has been adopted to produce Sn-based perovskite films. However, DMSO intrinsically oxidizes Sn2+ while fast antisolvent-dropping causes serious coupling between crystal nucleation and growth, leading to the easy formation of defects and poor stability of Sn-based perovskite films. Herein, hydrazine acetate (HAAc) ionic salt, possessing strong coordination ability with Sn2+, is developed to stabilize Sn2+ and decouple the crystallization by promoting pre-formed crystals (PFCs) in precursor solution and enabling the self-assembly of PFCs during spin-coating. The HAxFA1-xSnI3 films fabricated by this PFCs self-assembly technique show tunable bandgap, low defect density, and oriented crystals, producing optoelectronic devices with decent photovoltaic and electroluminescence performance. The DMSO-free one-step film-forming enabled by HAAc-assisted crystallization decoupling can open up new avenues for facile and low-cost manufacturing of efficient and stable optoelectronic devices adopting Sn-based perovskite films.

Solution deposition struggles to achieve conformal and pinhole-free wide-bandgap (WBG) perovskite films on micrometer-scale textured silicon subcells due to challenges in nucleation dynamics and film uniformity, necessitating smaller textures in the efficient perovskite/silicon tandems, which compromise light trapping and current density. While evaporation-assisted two-step deposition improves conformality, it often yields films with suboptimal crystallinity and a high defect density. To address this, we elucidate the formation mechanism of CsPbIxBr3-x nanocrystals during the thermal evaporation of PbI2/CsBr templates, which can serve as preferential nucleation sites to facilitate the growth of high-quality perovskite films. By optimizing evaporation conditions and incorporating 2,3,4,5,6-pentafluorobenzylphosphonic acid (pFBPA) during the spin-coating process, we achieved enhanced crystallization kinetics of nucleation sites and improved perovskite film uniformity. Further interface modification with pFBPA and ethane-1,2-diammonium iodide induces targeted surface dipoles at both carrier transport layers/perovskite interfaces, which not only offers better band alignment and surface passivation at both interfaces but also creates an enhanced electric field to boost electron extraction. These advancements enabled a WBG (1.68 eV) perovskite solar cell (PSC) to achieve an impressive power conversion efficiency (PCE) among WBG (1.65-1.7 eV) PSCs based on evaporation-assisted deposition. This study provides fundamental insights into achieving conformal high-quality WBG perovskite films, offering a theoretical foundation for the development of efficient perovskite/silicon tandems.

Ultrathin tandem solar cells have potential for a wide range of applications due to flexibility, high power-to-weight ratio, price competitiveness (low-cost and low capex). However, unlike standard tests under air-mass1.5 (AM1.5) 1 sun illumination, differences in spectral irradiance and incidence angle caused by spatio-temporal variation of solar light have significant effects on the tandem solar cells, especially on the ultrathin tandem solar cells, which are much more sensitive to incidence angle due to the sub-micro/micro textured structures. We develop a multiscale optical model and photovoltaic characteristic model for detailed description of photon propagation and carrier transport in the ultrathin tandem solar cells, respectively. Though analyses on the effect of inverted pyramid photonic crystal architecture on light absorption of the ultrathin tandem solar cells, the optimal structural parameters of inverted pyramid photonic crystal architecture are obtained, which leads to an improvement of the power conversion efficiency of ultrathin tandem solar cell by 0.82 % compared to the tandem solar cells with pristine thickness (similar to 180 mu m). Based on the optimized ultrathin tandem solar cells, detailed mechanisms of the effects of variation in regional and daily spectral irradiances on the PV characteristics are unravelled. Compared to daily spectral irradiance variations, regional spectral irradiance variations have a greater effect on the structural dimensions and performance of ultrathin tandem solar cells. However, in the daily solar light variations, incidence angle variation has a significant effect on ultrathin tandem solar cells, and this effect is primarily reflected in the bottom sub-cells. The unravelled mechanism of the effect of incidence angle variation helps us propose a recommendation to improve the daily output power of the ultrathin tandem solar cells (2312.30 W.h/m(2)) in the analyses under real-world condition.

Tin (Sn)-based perovskite field-effect transistors (FETs) have garnered considerable attention as promising candidates for next-generation electronics and optoelectronics due to their exceptional charge transport properties, cost-effectiveness, and eco-friendly nature. However, owing to facile Sn vacancy formation, serious oxidation as well as uncontrollable crystallization, Sn-based perovskites generally suffer from inferior film quality with high-density defects, resulting in unfavorable self-doping effects with high hole concentrations. Furthermore, defects within the relatively thin films (tens of nanometers) of these FETs, primarily located at the surface and grain boundaries (GBs) of perovskite films, significantly impact the charge transport, ion migration, and structural stability during device operation, thereby impeding the achievement of high-performance Sn-based perovskite FETs. Herein, a comprehensive overview of defect properties, origins, and their influence on the performance of Sn-based perovskite FETs is present. In particular, the advanced defect passivation strategies, including compositional engineering, dopant modification, dimensional engineering, interface passivation, and crystallization regulation are summarized systematically. Lastly, the existing challenges and potential future prospects regarding defect engineering are proposed to achieve high-performance Sn-based perovskite FETs, which will pave the way for further large-scale integration applications.

Solution-processed metal halide perovskites (MHPs) have been rapidly developed worldwide, with much attention to fluid dynamic, fluid crystallization, and fluid interfaces, all falling within the realm of fluid chemistry. It is widely recognized that the theory of fluid chemistry has been proven to provide an effective means for the improvement of perovskite crystallization and the enhancement of perovskite solar cells (PSCs) performance. In this review, the fluid behavior, microfluidic synthesis, and aging process of perovskite materials are first investigated, with emphasis on the related improvement methods and chemical mechanisms. Second, the internal crystallization chemistry, external interface chemistry, and the large-area PSCs based on the fluid chemistry are discussed. Finally, four specific directions for future studies of fluid chemistry of MHPs are proposed, aiming to harness the theoretical advantages of fluid chemistry and contribute to the industrialization of PSCs.

Currently, the latest photovoltaic technology based on perovskite solar cells (PSCs) has attracted much attention due to the low cost, exciting power conversion efficiency of over 26%, large scalability, and flexibility of PSCs. During the development course, optimization of the electron transport layer (ETL) plays an important role in boosting the photovoltaic performance of PSCs, where the use and modification of SnO2 with high chemical stability, low-temperature processability, and suitable energy band levels substantially are shown to solve the problems of poor charge transport, perovskite crystallization, and inferior stability at the PSC interface. Herein, we dedicate ourselves to providing a comprehensive review of the advanced development of the SnO2 ETL for realizing efficient PSCs. The fundamental properties of SnO2 and its key problems as an ETL in PSCs are summarized first. Then, the typical preparation methods are introduced, including chemical routes and physical routes. Sequentially, the state-of-the-art strategies for optimizing the quality of the SnO2 ETL are discussed, such as defect regulation, self-assembled monolayer modification, and double ETL construction. Finally, we shed some light on the existing challenges and future research directions for the large-scale development of SnO2-based PSCs.

Lead-tin（Pb-Sn） perovskites with an ideal bandgap of 1.34-1.40 eV show great promise in perovskite solar cells（PSCs）.Recently,to address the environmental pollution and Sn 2+ oxidation problems of dimethyl sulfoxide,methylammonium acetate（MAAc） ionic liquid has been developed as an alternative to fabricate ideal bandgap MAPb 0.7 Sn 0.3 I 3 （1.36 eV） film via hot-casting in air.However,the spontaneous crystallization of Pb-Sn perovskite initiated by heat-induced supersaturation is fast and random,setting critical challenges in regulating crystal growth during the film-forming process.Herein,a lattice activation strategy is developed to control the crystallization dynamics of MAPb 0.7 Sn 0.3 I 3 in MAAc to produce films with micrometer-sized grains in air.FA is shown to activate the crystal lattice that facilitates the formation of intermediates and balances the crystal growth of MAPb 0.7 Sn 0.3 I 3 ,producing films with a grain size of 2.78±0.17 μm.Furthermore,4-fluoro-phenethylammonium and phenethylammonium are adopted to passivate the defects in the film and promote the energy level alignment at the top interface,respectively.The optimized PSC device achieved an efficiency of 18.24% with a short-circuit current of 29.84 mA/cm 2 ,which are both the highest values in 1.3 6 eV Pb-Sn PSCs to date.Notably,the unencapsulated devices show excellent storage and air stability under various conditions.