RESUMO
Recently, solution-processed hybrid halide perovskite has emerged as promising materials for advanced optoelectronic devices such as photovoltaics, photodetectors, light emitting diodes and lasers. In the mean time, all-dielectric metasurfaces with high-index materials have attracted attention due to their low-loss and high-efficient optical resonances. Because of its tunable by composition band gap in the visible frequencies, organolead halide perovskite could serve as a powerful platform for realizing high-index, low-loss metasurfaces. However, direct patterning of perovskite by lithography-based technique is not feasible due to material instability under moisture. Here we report novel organolead halide perovskite metasurfaces created by the cost-effective thermal nanoimprint technology. The nanoimprinted perovskite metasurface showed improved surface morphology and enhanced optical absorption properties. Significantly enhanced optical emission with an eight-fold enhancement in photoluminescence (PL) intensity was observed under room temperature. Temperature-dependent PL of perovskite nanograting metasurface was also investigated. Based on our results, we believe that thermal nanoimprint is a simple and cost-effective technique to fabricate perovskite-based metasurfaces, which could have broad impact on optoelectronic and photonic applications.
RESUMO
Liquid-phase exfoliation of zirconium trisulfide (ZrS3) was used to produce stable and ready-to-use inks for solution-processed semiconductor thin-film deposition. Ribbon-like layered crystals of ZrS3 were produced by the chemical vapor transport method and were then exfoliated in three different solvents: dimethylformamide, ethanol, and isopropyl alcohol. The resulting ZrS3 dispersions were compared for stability and the ability to form continuous films on top of the perovskite layer in light-emitting diodes with the ITO/PEDOT:PSS/MAPbBr3/2D-ZrS3/LiF/Al structure. Film deposition was performed by using either spray or slot-die coating methods. The slot-die coating route proved to produce better and more uniform films with respect to spray coating. We found that the 2D ZrS3 electron injection layer (EIL) stabilized the interface between the perovskite and LiF/Al cathode, reducing the turn-on voltage to 2.8 V and showing a luminance that does not degrade during voltage sweep. On the other hand, EIL-free devices show electroluminescence on the first voltage sweep that reduces almost to zero in the subsequent sweeps. Combining physical device simulation and density functional theory calculation, we are able to explain these results in terms of lowering the electron injection barrier at the cathode.