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The electron injection rate in CdSe quantum dots sensitized solar cells: From bifunctional linker and zinc oxide morphology

Abstract

Herein, we have investigated the effect both of the bifunctional linker (L1, L2, L3, and L4) and ZnO morphology (porous nanoparticles (NPs), nanowires (NWs), and nanotubes (NTs-A and NTs-Z)) on the electron injection in CdSe QDs sensitized solar cell by first-principle simulation. Via calculating the partitioned interfaces formed by different components (linker/QDs and ZnO/linker), we found that the electronic states of QDs and every ZnO substrate are insensitive upon any linker capped, while the frontier orbitals of L1-L4 (with increased delocalization) manifest a systematical negative-shift. Because of the lowest unoccupied molecular orbital (LUMO) of L1 compared to its counterparts aligned in the region of the virtual states of QDs or substrate with a high density of states, it always yields a stronger electronic coupling with QDs and varied substrates. After characterization of the complete ZnO/linker/QDs system, we found that the electron injection time (τ) depends on both of the linker and substrate vastly. On the one hand, L1 bridged QDs and every substrate always achieve the shortest τ than its counterparts associated cases apparently. On the other hand, NWs supported systems always yield the shortest τ no matter what the linker is. Overall, the NWs/L1/QDs system achieves the fastest injection by ~160 fs. These essentially stem from the shortest molecular length of L1 decreasing the distance between QDs and substrate, subsequently improving the interfacial coupling. Meanwhile, the NWs supported cases generate the less sensitive virtual states for both of the QDs and NWs, ensuring a less variable interfacial coupling. These combined can provide a comprehension on the effect contributed from linker and oxide semiconductor morphology on charge transfer for aim of choosing appropriate component with fast directional electron injection.

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Supplementary files

Publication details

The article was received on 05 Jul 2017, accepted on 21 Sep 2017 and first published on 22 Sep 2017


Article type: Paper
DOI: 10.1039/C7NR04847E
Citation: Nanoscale, 2017, Accepted Manuscript
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    The electron injection rate in CdSe quantum dots sensitized solar cells: From bifunctional linker and zinc oxide morphology

    W. Ding, X. Peng, Z. Sun and Z. Li, Nanoscale, 2017, Accepted Manuscript , DOI: 10.1039/C7NR04847E

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