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Coherent plane-wave compounding (CPWC) has attracted significant attention in preclinical research and clinical diagnosis. However, a trade-off exists in CPWC between the image quality and frame rate. Null subtraction imaging (NSI), as a novel beamforming method, can realize high-quality imaging with enhanced lateral resolution and suppressed grating lobes. This study explores NSI to reduce the number of emissions while preserving the imaging quality. The performance of the proposed method is assessed using the Plane-Wave Imaging Challenge in Medical Ultrasound datasets, including phantom and in vivo datasets. The results verify the potential of NSI in terms of frame rate improvement compared to the conventional delay and sum beamforming method. NSI with 5 and 15 plane-wave emissions is evaluated. For example, for the experimental phantom datasets, NSI with 15 plane-wave emissions improves the lateral full-width at half maximum by 0.10 in comparison to DAS with 75 plane-wave emissions. Moreover, the corresponding contrast ratio and generalized contrast-to-noise ratio increase from 25.11 to 31.19 dB and 0.63 to 0.68, respectively, indicating contrast improvement. Thus, compared to DAS with 75 plane-wave emissions, the proposed method accelerates data acquisition by a factor of 5, resulting in remarkable frame rate improvement. [ABSTRACT FROM AUTHOR]

Perovskite/organic bulk heterojunction (BHJ) integrated solar cells have tremendous development potential to exceed the Shockley–Queisser limit efficiency of single-junction photovoltaics, due to the merits of spectra response extension. However, the presence of energy level barriers and severe non-radiative recombination at the interface between perovskite and BHJ greatly hindered the transport and collection of charge carriers, usually leading to large Voc and photocurrent loss, as well as the stability degradation of integrated devices. Therefore, investigating the interface properties of perovskite/BHJ is crucial for understanding the charge transport process and enhancing device performance. In this study, we effectively regulated the interface properties and charge transport in perovskite/BHJ integrated devices using a thermal annealing process. Using Kelvin probe microscopy, photoluminescence, and transient absorption spectroscopy, we revealed that moderate annealing treatment would contribute to forming close interface contact and provide more channels or pathways for charge transfer, which is advantageous for the interface charge collection and device performance. In addition, the lone pair electrons of acyl, thiophene and pyrrole function groups in polymer PDPP3T and PCBM can act as the Lewis base and provide electrons to the under-coordinated lead atoms or clusters in the perovskite, effectively passivating traps on the surface and grain boundaries of the perovskite through Lewis acid–base coordination. Finally, we improved the photovoltaic conversion efficiency of the device to 21.57% with enhanced stability using an optimized thermal annealing process. This study provides a comprehensive understanding of the integrated perovskite/BHJ interface properties, which could be extended to other optoelectronic devices based on a similar integrated structure. [ABSTRACT FROM AUTHOR]