Top-Down Induced Crystallization Orientation toward Highly Efficient p-i-n Perovskite Solar Cells.

Crystallization orientation plays a crucial role in determining the performance and stability of perovskite solar cells (PVSCs), whereas effective strategies for realizing oriented perovskite crystallization is still lacking. Herein, a facile and efficient top-down strategy is reported to manipulate the crystallization orientation via treating perovskite wet film with propylamine chloride (PACl) before annealing. The PA+ ions tend to be adsorbed on the (001) facet of the perovskite surface, resulting in the reduced cleavage energy to induce (001) orientation-dominated growth of perovskite film and then reduce the temperature of phase transition, meanwhile, the penetrating Cl ions further regulate the crystallization process. As-prepared (001)-dominant perovskite films exhibit the ameliorative film homogeneity in terms of vertical and horizontal scale, leading to alleviated lattice mismatch and lowered defect density. The resultant PVSC devices deliver a champion power conversion efficiency (PCE) of 25.07% with enhanced stability, and the unencapsulated PVSC device maintains 95% of its initial PCE after 1000 h of operation at the maximum power point under simulated AM 1.5G illumination.

Charge Management Enables Efficient Spontaneous Chromatic Adaptation Bipolar Photodetector.

Solution-processed photodetectors have emerged as promising candidates for next-generation of visible-near infrared (vis-NIR) photodetectors. This is attributed to their ease of processing, compatibility with flexible substrates, and the ability to tune their detection properties by integrating complementary photoresponsive semiconductors. However, the limited performance continues to hinder their further development, primarily influenced by the difference of charge transport properties between perovskite and organic semiconductors. In this work, a perovskite-organic bipolar photodetectors (PDs) is introduced with multispectral responsivity, achieved by effectively managing charges in perovskite and a ternary organic heterojunction. The ternary heterojunction, incorporating a designed NIR guest acceptor, exhibits a faster charge transfer rate and longer carrier diffusion length than the binary heterojunction. By achieving a more balanced carrier dynamic between the perovskite and organic components, the PD achieves a low dark current of 3.74 nA cm-2 at -0.2 V, a fast response speed of <10 µs, and a detectivity of exceeding 1012 Jones. Furthermore, a bioinspired retinotopic system for spontaneous chromatic adaptation is achieved without any optical filter. This charge management strategy opens up possibilities for surpassing the limitations of photodetection and enables the realization of high-purity, compact image sensors with exceptional spatial resolution and accurate color reproduction.

Highly Efficient Perovskite/Organic Tandem Solar Cells Enabled by Mixed-Cation Surface Modulation.

Perovskite/organic tandem solar cells (POTSCs) are gaining attention due to their easy fabrication, potential to surpass the S-Q limit, and superior flexibility. However, the low power conversion efficiencies (PCEs) of wide bandgap (Eg) perovskite solar cells (PVSCs) have hindered their development. This work presents a novel and effective mixed-cation passivation strategy (CE) to passivate various types of traps in wide-Eg perovskite. The complementary effect of 4-trifluoro phenethylammonium (CF3 -PEA+ , denoted as CA+ ) and ethylenediammonium (EDA2+ , denoted as EA2+ ) reduces both electron/hole defect densities and non-radiative recombination rate, resulting in a record open-circuit voltage (Voc ) of wide-Eg PVSCs (1.35 V) and a high fill factor (FF) of 83.29%. These improvements lead to a record PCE of 24.47% when applied to fabricated POTSCs, the highest PCE to date. Furthermore, unencapsulated POTSCs exhibit excellent photo and thermal stability, retaining over 90% of their initial PCE after maximum power point (MPP) tracking or exposure to 60 °C for 500 h. These findings imply that the synergic effect of surface passivators is a promising strategy to achieve high-efficiency and stable wide-Eg PVSCs and corresponding POTSCs.

MwdpNet: towards improving the recognition accuracy of tiny targets in high-resolution remote sensing image.

This study aims to develop a deep learning model to improve the accuracy of identifying tiny targets on high resolution remote sensing (HRS) images. We propose a novel multi-level weighted depth perception network, which we refer to as MwdpNet, to better capture feature information of tiny targets in HRS images. In our method, we introduce a new group residual structure, S-Darknet53, as the backbone network of our proposed MwdpNet, and propose a multi-level feature weighted fusion strategy that fully utilizes shallow feature information to improve detection performance, particularly for tiny targets. To fully describe the high-level semantic information of the image, achieving better classification performance, we design a depth perception module (DPModule). Following this step, the channel attention guidance module (CAGM) is proposed to obtain attention feature maps for each scale, enhancing the recall rate of tiny targets and generating candidate regions more efficiently. Finally, we create four datasets of tiny targets and conduct comparative experiments on them. The results demonstrate that the mean Average Precision (mAP) of our proposed MwdpNet on the four datasets achieve 87.0%, 89.2%, 78.3%, and 76.0%, respectively, outperforming nine mainstream object detection algorithms. Our proposed approach provides an effective means and strategy for detecting tiny targets on HRS images.