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2D lead halide perovskites (LHPs) show strong excitonic and spin‐orbit coupling effects, generating a facile spin injection. Besides, they possess a polaron character due to the soft crystal lattice, which can prolong the spin lifetime, making them favorable materials for spintronic applications. Here, the spin dynamics of 2D PEA2PbI4(MAPbI3)n−l thin films with different layers by temperature‐ and pump fluence–dependent circularly polarization‐resolved transient absorption (TA) measurements is studied. These results indicate that the spin depolarization mechanism is gradually converted from the Maialle–Silva–Sham (MSS) mechanism to the polaronic states protection mechanism with the layer number increasing from = 1 to 3, which is determined by the interplay between the strength of Coulomb exchange interaction and the strength of polaronic effect. While for ≥ 4, the Elliot–Yafet (EY) impurities mechanism is proposed, in which the formed polaronic states with free charge carriers no longer play the protective role. [ABSTRACT FROM AUTHOR]

The accumulation of heat in electronic devices puts forward an urgent demand for thermal interface materials. It is still a great challenge to achieve the good comprehensive performance of high thermal conductivity (TC), insulation, flexibility and tensile strength. In this work, polyester‐based nonwoven fabric (NWF) was coated with boron nitride nanosheets (BNNS) by dispersion and interfacial reinforcement of cellulose nanofibers to obtain a three‐dimensional thermally conductive network skeleton (BNNS@NWF). The sandwich‐structured composite film was assembled by introducing alumina (Al2O3)/polydimethylsiloxane (PDMS) layers on the top and bottom surfaces of BNNS@NWF using scratch coating and hot pressing processes. The composite film has a high TC of 6.42 W/mK at 45.8 wt% BNNS content, and has excellent insulation with a volume resistivity of 1.06 × 1015 Ω cm. This is due to the long‐range effective thermal conduction path constructed by BNNS, the bridging effect of Al2O3 and the synergistic effect of the two fillers. PDMS helps the composite film maintain good flexibility and good TC stability after 30 bending cycles. The PET nonwoven interlayer gives the composite film good mechanical properties with a tensile strength of 17.5 MPa. This work provides a strategy for the efficient preparation of flexible composite films with high TC and insulation properties, which is of great importance for the development of innovative thermal interface materials. Highlights: A sandwich‐structured composite film was prepared by a simple scale‐up method.Al2O3 and BNNS achieves synergistic enhancement of thermal conductivity.The film has a high thermal conductivity of 6.42 W/mK and electrical insulation.The film shows good flexibility, high tensile and thermal management properties. [ABSTRACT FROM AUTHOR]

Contrasting moisture evolutions between westerlies‐dominated Central Asia and monsoonal Asia since the mid‐Holocene have been widely recognized. Yet, inconsistent hydrological records over the early Holocene from both regions hamper our understanding of hydroclimatic changes and associated mechanisms. Here we present isotopic and biomarker (alkenone) records from three Chinese lakes located at both regions to address a possible meltwater role in lake water budget. Our results show the occurrence of particularly depleted isotopic values of lake water associated with lake freshening within the deglaciation and early Holocene. Together with anomalously old 14C dates, which were also documented in many other Asian lakes, our observations likely indicate substantial meltwater contribution to mid‐latitude Asian lake water budget, along with the climatic warming. Hence, the potential meltwater effect should be considered when inferring Asian summer monsoon and westerlies behavior over this critical period, with important implications to Holocene hydrological reconstructions and future hydroclimatic projections. Plain Language Summary: Although meltwater events have been well documented in marine records, the effects of meltwater on Asian lake water budget and regional hydrological cycle during the deglaciation and warm early Holocene remain poorly investigated. Our isotopic and biomarker records from Lake Sayram, Yanhaizi, and Qinghai in northern China, together with anomalously old 14C dates from investigated lakes and other Asian lakes, likely indicate substantial meltwater contribution to lake water budget within the deglaciation and early Holocene, which appears to be a large‐scale phenomenon in mid‐latitude Asia. This suggests that the potential meltwater effect on Asian lake hydrology should be assessed in climatic reconstructions and simulations, which may shed light on accurate interpretation of westerlies and summer monsoon circulation over the early Holocene. Key Points: Isotopic records likely indicate meltwater contribution to Asian lake water budget within the deglaciation and early HoloceneAnomalously old 14C dates summarized from mid‐latitude Asian lakes also support substantial meltwater input during this periodMeltwater effects should be considered when inferring early Holocene Asian summer monsoon and westerlies behavior [ABSTRACT FROM AUTHOR]

Half‐light and half‐matter exciton polaritons have demonstrated profound impacts on coherent quantum phenomena. Two‐dimensional (2D) organic−inorganic perovskite semiconductors, exhibiting large exciton binding energy and spin‐based behavior, are an excellent platform for the study of exciton polaritons at room temperature. However, the implementation of these fascinating coherent phenomena is still constrained by the lack of an understanding of the crucial polariton–polariton interaction effects. Here, an experimental observation of spin‐dependent polariton–polariton interactions in a prototype 2D organic−inorganic perovskite microcavity by circularly polarization‐resolved transient absorption (TA) measurements is reported. A power‐dependent blue shift of the lower polariton bands with the same spin is clearly revealed, whereas the energy band of the polariton bands with the opposite spin is almost not changed. Spectacularly, it is found that the energy band blue shift mainly takes place before the spin depolarization, which provides accurate evidence for the spin‐dependent polariton–polariton interactions. Furthermore, the strong coherent polariton–phonon coupling of perovskite microcavity has also been detected firstly in ultrafast TA dynamics. These results demonstrate that microcavity polaritons inheriting the matter properties from their excitonic constituents exhibit strong nonlinear interactions and pave the way for realizing coherent quantum phenomena at room temperature. [ABSTRACT FROM AUTHOR]