Stable Light-Emitting Diodes Using Phase-Pure Ruddlesden-Popper Layered Perovskites.

Tsai, Hsinhan; Nie, Wanyi; Blancon, Jean-Christophe; Stoumpos, Constantinos C; Soe, Chan Myae Myae; Yoo, Jinkyoung; Crochet, Jared; Tretiak, Sergei et al. · Adv Mater · 2018

basic_science · Level V

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Abstract

State-of-the-art light-emitting diodes (LEDs) are made from high-purity alloys of III-V semiconductors, but high fabrication cost has limited their widespread use for large area solid-state lighting. Here, efficient and stable LEDs processed from solution with tunable color enabled by using phase-pure 2D Ruddlesden-Popper (RP) halide perovskites with a formula (CH<sub>3</sub> (CH<sub>2</sub> )<sub>3</sub> NH<sub>3</sub> )<sub>2</sub> (CH<sub>3</sub> NH<sub>3</sub> )<sub>n</sub><sub>-1</sub> Pb<sub>n</sub> I<sub>3</sub><sub>n</sub><sub>+1</sub> are reported. By using vertically oriented thin films that facilitate efficient charge injection and transport, efficient electroluminescence with a radiance of 35 W Sr<sup>-1</sup> cm<sup>-2</sup> at 744 nm with an ultralow turn-on voltage of 1 V is obtained. Finally, operational stability tests suggest that phase purity is strongly correlated to stability. Phase-pure 2D perovskites exhibit >14 h of stable operation at peak operating conditions with no droop at current densities of several Amperes cm<sup>-2</sup> in comparison to mixtures of 2D/3D or 3D perovskites, which degrade within minutes.