Development of hole transport materials (HTMs) with comprehensive passivation effects and appropriate energy levels are urgently desirable for constructing highly efficient and stable perovskite solar cells (PSCs). Herein, we report an effective interfacial molecular doping strategy and energy level regulation approach to improve the performance of PSCs with ultrasimple carbazole-based HTMs CZ-As and CZ-Py. The pyridine-substituted HTM CZ-Py exhibits a stepped energy level with perovskite and CZ-As, effective passivation of Pb2+ defect, as well as the assistance of the formation of high-quality perovskite film and hole transport layer (HTL). By utilizing CZ-Py as interfacial doping material and CZ-As as HTM, the undesired charge carrier recombination at the perovskite/HTM interface are significantly restricted. Finally, the fabricated PSCs feature an impressive power conversion efficiency (PCE) up to 23.5% and good long-term stability. This work demonstrates a facile and highly efficient way to reduce nonradiative recombination and further improve photovoltaic performance of PSCs.

No abstract

Near‐infrared (NIR) fluorescent materials are considered to be the most promising labeling reagents for sensitive determination and biological imaging due to the advantages of lower background noise, deeper penetrating capacity, and less destructive effects on the biomatrix over those of UV and visible fluorophores. In the past decade, advances in biomedical fluorescence imaging in the NIR region have focused on the traditional NIR window (NIR‐I; λ=700–900 nm), and have recently been extended to the second NIR window (NIR‐II; λ=1000–1700 nm). In vivo NIR‐II fluorescence imaging outperforms imaging in the NIR‐I window as a result of further reduced absorption, tissue autofluorescence, and scattering. In this review, the applications of four types of NIR‐II fluorescent materials, organic fluorophores, quantum dots, rare‐earth compounds, and single‐walled carbon nanotubes, are summarized and future trends are discussed. Some methods to enhance the NIR‐II fluorescence quantum yield are also proposed.

Two D–A polymers with good NIR-II fluorescence, photoacoustic and photothermal properties were designed and synthesized.