Spontaneous Self‐Assembly of Perovskite Nanocrystals into Electronically Coupled Supercrystals: Toward Filling the Green Gap

• Published in: Advanced materials (Weinheim) Vol. 30; no. 29; pp. e1801117 - n/a
• Main Authors: Tong, Yu, Yao, En‐Ping, Manzi, Aurora, Bladt, Eva, Wang, Kun, Döblinger, Markus, Bals, Sara, Müller‐Buschbaum, Peter, Urban, Alexander S., Polavarapu, Lakshminarayana, Feldmann, Jochen
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 19.07.2018
• Subjects: Assembly; Color; CsPbX3 perovskite; electronic coupling; Emission; Emitters; green LEDs; Ion exchange; Light emission; Nanocrystals; Nanotechnology devices; Optical properties; Optoelectronics; Perovskites; Photoluminescence; Red shift; Substrates; supercrystals; superlattices; green LEDs; electronic coupling; supercrystals; CsPbX3 perovskite; superlattices
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.201801117

Self‐assembly of nanoscale building blocks into ordered nanoarchitectures has emerged as a simple and powerful approach for tailoring the nanoscale properties and the opportunities of using these properties for the development of novel optoelectronic nanodevices. Here, the one‐pot synthesis of CsPbBr3 perovskite supercrystals (SCs) in a colloidal dispersion by ultrasonication is reported. The growth of the SCs occurs through the spontaneous self‐assembly of individual nanocrystals (NCs), which form in highly concentrated solutions of precursor powders. The SCs retain the high photoluminescence (PL) efficiency of their NC subunits, however also exhibit a redshifted emission wavelength compared to that of the individual nanocubes due to interparticle electronic coupling. This redshift makes the SCs pure green emitters with PL maxima at ≈530–535 nm, while the individual nanocubes emit a cyan‐green color (≈512 nm). The SCs can be used as an emissive layer in the fabrication of pure green light‐emitting devices on rigid or flexible substrates. Moreover, the PL emission color is tunable across the visible range by employing a well‐established halide ion exchange reaction on the obtained CsPbBr3 SCs. These results highlight the promise of perovskite SCs for light emitting applications, while providing insight into their collective optical properties. The synthesis and spontaneous self‐assembly of perovskite nanocrystals (NCs) into supercrystals (SCs) at high colloid concentration takes place in one‐pot, starting with precursor powders. The perovskite SCs exhibit redshifted photoluminescence (PL) toward bulk like optical properties while maintaining the high PL quantum yields of the NCs. Using the CsPbBr3 SCs, the fabrication of LEDs with pure green emission is demonstrated.