Light-sensitive monolayer-thick nanocrystal skins of face-down self-oriented colloidal quantum wells.

Colloidal quantum wells (CQWs), a quasi-two-dimensional, atomically-flat sub-family of semiconductor nanocrystals, are well suited to produce excellent devices for photosensing applications thanks to their extraordinarily large absorption cross-sections. In this work, we propose and demonstrate a new class of light-sensitive nanocrystal skins (LS-NS) that employ a monolayer of face-down orientation-controlled self-assembled CQWs as the active absorbing layer in the UV-visible range. This CQW LS-NS platform enables non-conventional photosensing operation that relies on the strong optical absorption of the monolayered assembly of CQWs and the subsequent photogenerated potential build-up across the device, allowing for self-powered operation.

On the Rational Design of Core/(Multi)-Crown Type-II Heteronanoplatelets.

Solution-processed two-dimensional nanoplatelets (NPLs) allowing lateral growth of a shell (crown) by not affecting the pure confinement in the vertical direction provide unprecedented opportunities for designing heterostructures for light-emitting and -harvesting applications. Here, we present a pathway for designing and synthesizing colloidal type-II core/(multi-)crown hetero-NPLs and investigate their optical properties. Stoke's shifted broad photoluminescence (PL) emission and long PL lifetime (∼few 100 ns) together with our wavefunction calculations confirm the type-II electronic structure in the synthesized CdS/CdSeTe core/crown hetero-NPLs.