We report on an innovative route to increase the upconversion (UC) green radiation by two orders of magnitude in Y2O3:Er3+ nanocrystals through tailoring Er3+ ions’ local environment with Li+ ions under diode laser excitation of 970nm. Theoretical investigations based on the steady-state rate equations indicate that such enhancement arises from a combining effect of the tailored lifetime of the intermediate I11∕24(Er) state, the suppressed cross relaxation H11∕22(Er)+I15∕24(Er)→I9∕24(Er)+I13∕24(Er) process, and the enlarged nanocrystal size induced by the Li+ ions. The proposed route here may constitute a promising step to solve the low efficiency problem in UC materials.

To develop fluorescent labels for multicolor imaging, rare-earth-ion-doped ZrO 2 nanocrystals were prepared by a complex precursor method. Laser excitation of 976 nm induced single fluorescent bands of green and red upconversion ͑UC͒ in ZrO 2 :Er 3+ and ZrO 2 :Er 3+ +Yb 3+ nanocrystals, respectively. A suppression ratio ͑SR͒ parameter was introduced, defined as the UC intensity ratio of the main band to all the other detected impurity bands, and SR values in the order of 10-100 were experimentally obtained, demonstrating the excellent monochromaticity of the UC labels. Thus, the two-color UC labels obtained are potentially ideal to be used for biological multicolor imaging.

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Black phosphorus (BP) has been considered as a promising two-dimensional (2D) semiconductor beyond graphene owning to its tunable direct bandgap and high carrier mobility. However, the hole-transport-dominated characteristic limits the application of BP in versatile electronics. Here, we report a stable and complementary metal oxide semiconductor (COMS) compatible electron doping method for BP, which is realized with the strong fieldinduced effect from the K + center of the silicon nitride (Si x N y ). An obvious change from pristine p-type BP to n type is observed after the deposit of the Si x N y on the BP surface. This electron doping can be kept stable for over 1 month and capable of improving the electron mobility of BP towards as high as ~176 cm 2 V -1 s -1 . Moreover, high-performance in-plane BP p-n diode and further logic inverter were realized by utilizing the n-doping approach. The BP p-n diode exhibits a high rectifying ratio of ~10 4 . And, a successful transfer of the output voltage from "High" to "Low" with very few voltage loss at various working frequencies were also demonstrated with the constructed BP inverter. Our findings paves the way for the success of COMS compatible technique for BP-based nanoelectronics.

Undoped and Eu-doped (1, 3 and 5 mol%) PbZrO 3 (PZ) antiferroelectric (AFE) thin films have been deposited on Pt (111)/ Ti/SiO 2 /Si substrates by a sol-gel method. The effect of Eu doping on phase transformation and energy storage performance of PZ thin films have been investigated in detail. It has been seen that on extent of Eu dopant the Curie temperature and electric field-induced phase transformation can be altered. The energy storage properties have been found to be strongly dependent on Eu doping content. With the increase of Eu contents, recoverable energy storage density has been enhanced followed by their subsequent reduction. A maximum energy density (~18.8 J/cm 3 at~900 kV/cm) and minimum energy loss (~7.3 J/cm 3 ) have been achieved on 3 mol% Eu-doped PZ thin films.