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Self‐protective carbonized polymer dots (CPDs) with advantageous crosslinked nano‐structures have attracted considerable attention in metal‐free room temperature phosphorescence (RTP) materials, whereas their RTP emissions are still limited to short wavelength. Expanding their RTP emissions to Near‐Infrared (NIR) range is attractive but suffers from the difficulties in constructing narrow energy levels and inhibiting intense non‐radiative decay. Herein, a crosslink‐enhanced emission (CEE)‐dominated construction strategy was proposed, achieving desired NIR RTP (710 nm) in self‐protective CPDs for the first time. Structural factors, i.e. crosslinking (covalent‐bond CEE), conjugation (conjugated amine with bridging N−H and C=C group), and steric hindrance (confined‐domain CEE), were confirmed indispensable for triggering NIR RTP emission in CPDs. Contrast experiments and theoretical calculations further revealed the rationality of the design strategy originating from CEE in terms of promoting the narrow energy level emission of triplet excitons and inhibiting the non‐radiative quenching. This work not only firstly achieves NIR RTP in self‐protective CPDs but also helps understand the origin of NIR RTP to further guide the synthesis of diverse CPDs with efficient long‐wavelength RTP emission. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs), as a kind of zero‐dimensional nanomaterials, have been widely synthesized by bottom‐up methods from various precursors. However, the formation mechanism is still unclear and controversial, which also brings difficulty to the regulation of structures and properties. Only some tentative formation processes were postulated by analyzing the products obtained at different reaction times and temperatures. Here, the effect of crosslinking on the formation of carbonized polymer dots (CPDs) is explored. Crosslinking‐induced nucleation and carbonization (CINC) is proposed as the driving force for the formation of CPDs. Under hydrothermal synthesis, the precursors are initiated to polymerize and crosslink. The crosslinking brings higher hydrophobicity to generate the hydrophilic/hydrophobic microphase separation, which promotes dehydration and carbonization resulting in the formation of CPDs. Based on the principle of CINC, the influence factors of size are also revealed. Moreover, the dissipative particle dynamics (DPD) simulation is employed to support this formation mechanism. This concept of CINC will bring light to the formation process of CPDs, as well as facilitate the regulation of CPDs' size and photoluminescence. [ABSTRACT FROM AUTHOR]

Developing a facile strategy to realize fine‐tuning of phosphorescence color in time‐dependent room temperature phosphorescence (RTP) materials is essential but both theoretically and practically rarely exploited. Through simultaneously confining carboxyl dimer association and isolated carboxyl into the particle via a simple hydrothermal treatment of polyacrylic acid, a dual‐peak emission of red phosphorescence (645 nm) and green phosphorescence (550 nm) was observed from carbonized polymer dots (CPDs). The ratio of the two luminescent species can be well regulated by hydrochloric acid inhibiting the dissociation of carboxyl to promote hydrogen bond. Due to comparable but different lifetimes, color‐tunable time‐dependent RTP with color changing from yellow to green or orange to green were obtained. Based on the crosslinking enhanced emission effect, the phosphorescence visible time was even extended to 7 s through introducing polyethylenimide. This study not only proposes a novel and facile method for developing CPDs with color‐tunable time‐dependent RTP, but also provides a bran‐new non‐conjugated red phosphorescence unit and its definite structure. [ABSTRACT FROM AUTHOR]

The low‐dimensional halide perovskites have attracted increasing attention due to their improved moisture stability, reduced defects, and suppressed ions migration in many optoelectronic devices such as solar cells, light‐emitting diodes, X‐ray detectors, and so on. However, they are still limited by their large band gap and short charge carriers' diffusion length. Here, we demonstrate that the introduction of metal ions into organic interlayers of two‐dimensional (2D) perovskite by cross‐linking the copper paddle‐wheel cluster‐based lead bromide ([Cu(O2C−(CH2)3−NH3)2]PbBr4) perovskite single crystals with coordination bonds can not only significantly reduce the perovskite band gap to 0.96 eV to boost the X‐ray induced charge carriers, but can also selectively improve the charge carriers' transport along the out‐of‐plane direction and blocking the ions motion paths. The [Cu(O2C−(CH2)3−NH3)2]PbBr4 single‐crystal device can reach a record charges/ions collection ratio of 1.69×1018±4.7 % μGyair−1 s, and exhibit a large sensitivity of 1.14×105±7% μC Gyair−1 cm−2 with the lowest detectable dose rate of 56 nGyair s−1 under 120 keV X‐rays irradiation. In addition, [Cu(O2C−(CH2)3−NH3)2]PbBr4 single‐crystal detector exposed to the air without any encapsulation shows excellent X‐ray imaging capability with long‐term operational stability without any attenuation of 120 days. [ABSTRACT FROM AUTHOR]

This work reports the successful preparation of a new type of crystalline luminescent organic nanodot (<3.5 nm) by kinetically trapped self‐assembly, which is then used as a simplified π‐packing model to simulate the structure of CDs. The precise structure and J‐aggregation‐induced photoluminescence (PL) of the nanodots are revealed by investigating the structural relationship between the nanodots and the corresponding single crystals and their properties. Compared with the single crystals, crystalline organic nanodots show longer PL lifetime, higher PL quantum yield, and narrower PL peak, indicating that they are potential organic quantum nanodots. In addition, the efficient π‐stacking environment in the corresponding single crystals can promote π‐aggregation‐induced PL anisotropy. This work indicates crystalline organic nanodots with precise structures to be potentially useful for understanding the structures of CDs and to be attractive potential luminescent materials. [ABSTRACT FROM AUTHOR]

Hybrid organic/inorganic perovskite solar cells have been rapidly evolving with spectacular successes in both nanostructured and thin-film versions. Herein, we report the use of a simple sol-gel-processed NiO nanocrystal (NC) layer as the hole-transport layer in an inverted perovskite solar cell. The thin NiO NC film with a faceted and corrugated surface enabled the formation of a continuous and compact layer of well-crystallized CH3NH3PbI3 in a two-step solution process. The hole-extraction and -transport capabilities of this film interfaced with the CH3NH3PbI3 film were higher than those of organic PEDOT:PSS layers. The cell with a NiO NC film with a thickness of 30-40 nm exhibited the best performance, as a thinner layer led to a higher leakage current, whereas a thicker layer resulted in a higher series resistance. With the NiO film, we observed a cell efficiency of 9.11%, which is by far the highest reported for planar perovskite solar cells based on an inorganic hole-extracting layer. [ABSTRACT FROM AUTHOR]

The article discusses a study regarding the self-assembly of gold (Au15) into single-cluster-thick sheets at the interface of high-boiling solvents. It says that Au nanoclusters (NCs) with hydrophobic alkylthiols were adopted for the two-dimensional (2D) self-assembly in solvents with a slight polarity difference. It adds that the self-assembly of (Au15) clusters on diversified architectures is induced by the addition of liquid paraffin (LP).