| 초록 |
Due to extremely narrow luminous spectrum (full-width at half maximum (FWHM) ＜ 20nm), i.e., high color purity, lead halide perovskite has emerged as a candidate for next-generation light emitting diodes (LEDs). Especially, all-inorganic CsPbX3 (X=Br, I) emitters have showed the photoluminescence quantum yield (PLQY) of near-unity for green and red-light emission. However, further research is required for blue light materials with relatively low light-emitting performance. By moderately exchanging Br to Cl in CsPbBr3, the light emission spectrum can be matched to the blue-light emission. nonetheless, the mixed halide component, CsPbBr3-xClx, suffers from phase segregation due to easily ion migration, which introduces low PLQY and poor spectral stability. Here, we show a synthesis method of low-dimensional CsPbBr3 nanoplatelets (NPLs) that is efficient at emitting blue light without the need for halide-substitution. CsPbBr3 NPLs with 2 monolayer (ML) and 3 ML of thickness yielded PL peak at 435nm with very narrow FWHM of ~ 15 nm and PL peak at 456nm with FWHM of ~ 20 nm, respectively. To improving optical properties of these NPLs, we conducted post-synthesis treatment with tetrafluoroborate salts—almost 10-fold increase in PLQY was observed without major spectral change. Details and discussion of the results behind the improvement with the post-synthesis treatment will be described. |
