Aggregation-induced emission in lamellar solids of colloidal perovskite quantum wells

Jakub Jagielski, Sudhir Kumar, Mingchao Wang, Declan Scullion, Robert Lawrence, Yen-Ting Li, Sergii Yakunin, Tian Tian, Maksym V. Kovalenko, Yu-Cheng Chiu, Elton J. G. Santos, Shangchao Lin (+1 others)
2017 Science Advances  
The outstanding excitonic properties, including photoluminescence quantum yield (h PL ), of individual, quantumconfined semiconductor nanoparticles are often significantly quenched upon aggregation, representing the main obstacle toward scalable photonic devices. We report aggregation-induced emission phenomena in lamellar solids containing layer-controlled colloidal quantum wells (QWs) of hybrid organic-inorganic lead bromide perovskites, resulting in anomalously high solid-state h PL of up to
more » ... state h PL of up to 94%. Upon forming the QW solids, we observe an inverse correlation between exciton lifetime and h PL , distinct from that in typical quantum dot solid systems. Our multiscale theoretical analysis reveals that, in a lamellar solid, the collective motion of the surface organic cations is more restricted to orient along the [100] direction, thereby inducing a more direct bandgap that facilitates radiative recombination. Using the QW solids, we demonstrate ultrapure green emission by completely downconverting a blue gallium nitride light-emitting diode at room temperature, with a luminous efficacy higher than 90 lumen W −1 at 5000 cd m −2 , which has never been reached in any nanomaterial assemblies by far. RESULTS AND DISCUSSION Here, we report, to our knowledge, the first low-dimensional semiconductor system that exhibits the aggregation-induced emission (AIE) behavior (31) in lamellar solids containing layer-controlled colloidal QWs (CQWs) of OIHPs. The layer-controlled, monodispersed CQWs, with the formula (C 8 H 17 NH 3 ) 2 [APbBr 3 ] n PbBr 4 , where A is an organic cation and n is the stacking number of perovskite unit cells (32-34), were synthesized and dispersed in toluene by optimizing the protocols developed in our previous work (33). Note that although the CQWs share the same chemical form with the two-dimensional (2D) Ruddlesden-Popper perovskites (RPPs) (35), because of the nature
doi:10.1126/sciadv.aaq0208 pmid:29282451 fatcat:hq4etpntpbejzbnp3qoiaz4qdm