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Insight into the effect of ligand-exchange on colloidal CsPbBr3 perovskite quantum dot/mesoporous-TiO2 composite-based photodetectors: much faster electron injection

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Abstract

In the current work, we fabricate an all-inorganic perovskite quantum dot-based photodetector with bifunctional linker molecules, which is highly superior to its counterpart without the linker. The ultrahigh on/off ratio of 105 is two orders of magnitude higher than that of the device without the ligand treatment. Moreover, the responsivity increases from ∼2.2 A W−1 to ∼24.5 A W−1 and the detectivity from 3.5 × 1012 Jones to 8.9 × 1013 Jones. To gain further insight into the effect of ligand-exchange by bifunctional linker molecules besides surface passivation, we divide the electron transfer process into two parts, the electron transfer from quantum dots (QDs) to the linker and from the linker to TiO2. Injection of photoexcited electrons from colloidal CsPbBr3 QDs into TiO2 nanoparticles by bifunctional linker molecules is found to be much faster. Continuous-wave and time-resolved fluorescence spectra exhibit strong quenching for CsPbBr3 QDs assembled by the linker or coupled to TiO2 nanoparticles, which is consistent with electron transfer for QDs. From the results of the transient absorption measurement and fluorescence lifetime, the electron transfer time of QDs–TiO2 linked by the bifunctional molecules is calculated to be within 40 ns, while that from QDs to TiO2 particles directly is estimated to be ∼290 ns. This indicates that much faster electron injection occurs under the effect of the electron linker. In addition, the linker molecule modification can improve the adsorption of mp-TiO2 to capture more QDs.

Graphical abstract: Insight into the effect of ligand-exchange on colloidal CsPbBr3 perovskite quantum dot/mesoporous-TiO2 composite-based photodetectors: much faster electron injection

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Publication details

The article was received on 13 Apr 2017, accepted on 23 May 2017 and first published on 24 May 2017


Article type: Paper
DOI: 10.1039/C7TC01611E
Citation: J. Mater. Chem. C, 2017, Advance Article
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    Insight into the effect of ligand-exchange on colloidal CsPbBr3 perovskite quantum dot/mesoporous-TiO2 composite-based photodetectors: much faster electron injection

    L. Zhou, K. Yu, F. Yang, H. Cong, N. Wang, J. Zheng, Y. Zuo, C. Li, B. Cheng and Q. Wang, J. Mater. Chem. C, 2017, Advance Article , DOI: 10.1039/C7TC01611E

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