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A Layer‐by‐Layer ZnO Nanoparticle–PbS Quantum Dot Self‐Assembly Platform for Ultrafast Interfacial Electron Injection
Author(s) -
Eita Mohamed,
Usman Anwar,
ElBallouli Ala'a O.,
Alarousu Erkki,
Bakr Osman M.,
Mohammed Omar F.
Publication year - 2015
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201400939
Subject(s) - materials science , quantum dot , femtosecond , ultrafast laser spectroscopy , nanotechnology , nanoparticle , optoelectronics , electron acceptor , acceptor , semiconductor , solar cell , layer by layer , layer (electronics) , electron transfer , spectroscopy , photochemistry , optics , chemistry , laser , physics , condensed matter physics , quantum mechanics
Absorbent layers of semiconductor quantum dots (QDs) are now used as material platforms for low‐cost, high‐performance solar cells. The semiconductor metal oxide nanoparticles as an acceptor layer have become an integral part of the next generation solar cell. To achieve sufficient electron transfer and subsequently high conversion efficiency in these solar cells, however, energy‐level alignment and interfacial contact between the donor and the acceptor units are needed. Here, the layer‐by‐layer (LbL) technique is used to assemble ZnO nanoparticles (NPs), providing adequate PbS QD uptake to achieve greater interfacial contact compared with traditional sputtering methods. Electron injection at the PbS QD and ZnO NP interface is investigated using broadband transient absorption spectroscopy with 120 femtosecond temporal resolution. The results indicate that electron injection from photoexcited PbS QDs to ZnO NPs occurs on a time scale of a few hundred femtoseconds. This observation is supported by the interfacial electronic‐energy alignment between the donor and acceptor moieties. Finally, due to the combination of large interfacial contact and ultrafast electron injection, this proposed platform of assembled thin films holds promise for a variety of solar cell architectures and other settings that principally rely on interfacial contact, such as photocatalysis.