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This study seeks to enhance the classification performance of breast ultrasound images, addressing the challenges of difficult and costly collection of breast ultrasound datasets as well as the discrepancies in feature distribution of the collected datasets. Performance is enhanced by using a mix of generative adversarial networks (GAN) and domain adaptive networks. First, an adaptive layer is first added to the basic model of the gradually vanishing bridge (GVB), to better match the feature distributions of the source and target domains of the dataset. The multi-kernel maximum mean discrepancy (MK-MMD), which is the most efficient of existing adaptive approaches, is implemented in the fully connected layer of the original model's feature extraction network. Finally, through the process of fine-tuning, the model that has the highest level of overall performance is determined. In experiments, the proposed method surpassed the conventional unsupervised domain adaptation (DDC) and adversarial domain adaptation (MK_DAAN, GVB) in performance, achieving 85.11% accuracy, 97.48% recall, and 0.92 F1-score. [ABSTRACT FROM AUTHOR]

In most perovskite nanocrystal (PeNC)-based optoelectronic and photonic applications, surface ligands inevitably lead to a donor–bridge–acceptor charge transfer configuration. In this article, we demonstrate successful modulation of electron transfer (ET) rates from all-inorganic CsPbBr3 PeNCs to mesoporous titanium dioxide films, by using different surface ligands including single alkyl chain oleic acid and oleylamine, cross-linked insulating (3-aminopropyl)triethoxysilane and aromatic naphthoic acid molecules as the ligand-bridge. We systematically investigated the ET process through time-resolved photoluminescence spectroscopy. Calculations verified the ligand-bridge barrier effect of the three species upon the ET process. Transient absorption measurements excluded carrier-delocalization effect of the naphthoic acid ligands and confirmed the bridge-barrier effect. Our work provides a perspective for composable and appropriate ligands design for diverse practical purposes.

Perovskite/silicon tandem solar cells (TSCs) have aroused much attentions in recent years. One of keys for achieving highly efficient and stable TSCs is to guarantee effective charge transfer, especially on the rough textured silicon substrate due to the poor adhesion between interlayers. Here, a 2‐fluoroisonicotinic acid (2‐FNA) additive that possesses fluorine (‐F), carboxylic acid (‐COOH), and pyridine nitrogen as functional groups in the perovskite precursor to assist the crystallization process is utilized. It shows that 2‐FNA can efficiently reduce the defects and suppress non‐radiative recombination of perovskite layers by bonding with the uncoordinated Pb2+ ions, formamidinium (FA+), and halide vacancies, leading to notably prolonged carrier lifetime. Most importantly, this found that 2‐FNA aids in the formation of better interfacial contact between the perovskite and C60 layer on top, thus enhancing the interfacial electron extraction therein, eventually leading to an increased power conversion efficiency (PCE) of 28.61% on champion perovskite/silicon TSCs from 27.08% on control counterparts. This work provides a practical route to further advance the PV performance and applicability of perovskite/silicon TSCs. [ABSTRACT FROM AUTHOR]

Organic–inorganic lead halide perovskites have attracted great interest as low-cost and high efficiency solar cells. However, the excessive surface defects of perovskite crystal grains are still a crucial factor that limits further improvement in the performance of corresponding devices. Here, we introduce potassium chloride (KCl) into the precursor of a triple A-cation mixed-halide perovskite to passivate the surface defects and provide an insight into the underlying passivation mechanism of this common salt. We reveal that KCl exists on the surface of perovskite grains, suppressing the grain surface defects and modulating the energy level alignment of the perovskite solar cell (PSC). KCl added PSCs achieved a high open circuit voltage of 1.162 V compared with that of a control device (1.087 V), due to suppressed non-radiative recombination losses. Our work investigates the synergetic effect of K+ and Cl− on the enhancement of the device performance and provides an effective strategy of defect passivation toward highly efficient perovskite solar cells. [ABSTRACT FROM AUTHOR]

The photovoltaic (PV) performance of perovskite solar cells (PSCs) has rapidly advanced in the recent years; yet, the stability issue remains one of the last‐mile challenges on the road to commercialization. Charge transport layers and their interfaces with perovskites stand for critical tuning knobs that determine the device stability of PSCs. This review focuses on the effects of modification of SnO2 electron transport layers (ETLs) on the interfacial physicochemical properties and stability of PSC devices. In detail, the intrinsic defects, surface hydroxyls, and nonuniform morphology of SnO2 will negatively impact its interfacial physicochemical properties, thus degrading the device stability of PSCs. To tackle these existing issues, three modification approaches, such as surface morphology control, surface physicochemical modifications, and surface composite‐structure design, are categorized. Lastly, future perspectives in further promoting the stability of PSCs from SnO2 ETLs are raised based on the currently unresolved issues from both material and device levels. [ABSTRACT FROM AUTHOR]