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  1. Low‐dimensional thermoelectric materials systems are proven to possess improved thermoelectric performance, either by enhancing the power factorS2σthrough quantum confinement, or decreasing thermal conductivity with numerous interfaces. The 2D tellurium, also called tellurene, is a newly discovered 2D material which showed great potential for thermoelectric applications. In this article, high‐quality tellurene‐like nanosheets are synthesized by the hydrothermal method and assembled into nanostructured bulk materials by low‐temperature hot press, and their thermoelectric performance is investigated. Ultraviolet–ozone treatment is used to remove organic surface ligands. Doping is realized with surface doping with chalcogenidometalates. It is found that the Seebeck coefficient and the thermal conductivity of the nanosheet‐assembled bulk samples increased by ≈20% and decreased by 43% compared to bulk tellurium, respectively. Meanwhile, the carrier mobility is approaching, yet still lower than bulk tellurium. Overall, the best bulk sample possesses azTof 0.1 at room temperature which is comparable to bulk Te. By further improving the mobility, this solution processable material can provide useful thermoelectric performance for room‐temperature applications.

     
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    Controlled energy transfer has been found to be one of the most effective ways of designing tunable and white photoluminescent phosphors. Utilizing host emission to achieve the same would lead to a new dimension in the design strategy for novel luminescent materials in solid state lighting and display devices. In this work, we have achieved controlled energy transfer by suppressing the host to dopant energy transfer in La 2 Hf 2 O 7 :Eu 3+ nanoparticles (NPs) by co-doping with uranium ions. Uranium acts as a barrier between the oxygen vacancies of the La 2 Hf 2 O 7 host and Eu 3+ doping ions to increase their separation and reduce the non-radiative energy transfer between them. Density functional theory (DFT) calculations of defect formation energy showed that the Eu 3+ dopant occupies the La 3+ site and the uranium ion occupies the Hf 4+ site. Co-doping the La 2 Hf 2 O 7 :Eu 3+ NPs with uranium ions creates negatively charged lanthanum and hafnium vacancies making the system highly electron rich. Formation of cation vacancies is expected to compensate the excess charge in the U and Eu co-doped La 2 Hf 2 O 7 NPs suppressing the formation of oxygen vacancies. This work shows how one can utilize the full color gamut in the La 2 Hf 2 O 7 :Eu 3+ ,U 6+ NPs with blue, green and red emissions from the host, uranium and europium, respectively, to produce near perfect white light emission. 
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