Sensitized solar cells with colloidal PbS-CdS core-shell quantum dots Lai, Lai-Hung; Protesescu, Loredana; Kovalenko, Maksym V.

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1 University of Groningen Sensitized solar cells with colloidal PbS-CdS core-shell quantum dots Lai, Lai-Hung; Protesescu, Loredana; Kovalenko, Maksym V.; Loi, Maria Published in: Physical Chemistry Chemical Physics DOI: /c3cp54145b IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from it. Please check the document version below. Document Version Publisher's PDF, also known as Version of record Publication date: 14 Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Lai, L-H., Protesescu, L., Kovalenko, M. V., & Loi, M. A. (14). Sensitized solar cells with colloidal PbS- CdS core-shell quantum dots. Physical Chemistry Chemical Physics, 16(2), DOI: /c3cp54145b Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons). Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Downloaded from the University of Groningen/UMCG research database (Pure): For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Download date:

2 ASSOCIATE CONTENT Supporting Information Sensitized Solar Cells with Colloidal PbS/CdS Core/Shell Quantum Dots Lai-Hung Lai, a Loredana Protesescu, b,c Maksym V. Kovalenko b,c and Maria Antonietta Loi a a Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen, 9747 AG, The Netherlands b Department of Chemistry and Applied Biosciences, ETH Zürich, Wolfgang-Pauli-Str. 10, Zurich, 8093, Switzerland c EMPA-Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, Dübendorf, 8600, Switzerland Figure S1. PbS/CdS (1.1 nm) QD sensitized solar cells in the polysulfide electrolyte with and without methanol. 13 1

3 14 15 Figure S2. Absorbance of oleic-acid passivated colloidal QDs in chloroform. 16 2

4 R%, T% and A% A% R% T% Electronic Supplementary Material (ESI) for Physical Chemistry Chemical Physics 17 (a) 30 R% PbS R% PbS/CdS(0.5nm) R% PbS/CdS(1.1nm) A% PbS A% PbS/CdS(0.5nm) A% PbS/CdS(1.1nm) Wavelength (nm) 100 (b) PbS PbS/CdS(0.5nm) PbS/CdS(1.1nm) Wavelength (nm) (c) R% T% A% Wavelength (nm) Figure S3. (a) Reflectance and transmittance of QD sensitized electrodes (Glass/FTO/TiO 2 /QDs) (b) Absorbance spectra of QD sensitized electrodes (TiO 2 /QDs) (c) Reflection, transmission and absorption of Glass/FTO substrate. 3

5 Figure S4. (a) Nyquist plot of IMVS spectra of PbS/CdS(1.1nm) QD sensitized solar cells, measured by employing a 528 nm LED, scanned from 10 ma (corresponding to 0.22mW/cm 2 light intensity) to 500 ma (corresponding to mw/cm 2 light intensity). (b) Light intensity dependent mean electron lifetime 29 determined by IMVS measured under 528 nm LED illumination. 4

6 30 31 Figure S5. Charge injection efficiencies for cells with different CdS shell 32 thicknesses. The charge injection efficiency is obtained by, where 33 the is measured at 10 mw/cm 2 (Table S1) is used

7 36 Table S1. Equivalent circuit fitting results and other parameters of cells a Light Intensity c μ b r ct c r r d τ n e τ d f D e g μ e h L d i η c j mwcm -2 μfcm -2 μm -1 Ω cm 2 μm -1 Ω cm 2 μm ms ms m 2 s -1 cm 2 V -1 s -1 μm % PbS E E E E E E E E E E E E E E E E E E PbS/CdS(0.5nm) E E E E E E E E E E E E E E E E E E PbS/CdS(1.1nm) E E E E E E E E E E E E E E E E E E a values are determined based on the data measured at open-circuit condition under different light intensity by transmission line model fitting as the equivalent circuit shown in Fig. 3a. b the chemical capacitance per cm 2 produced by the accumulation of electrons in the TiO 2 and interface, C μ (= c μ L), where L is the thickness of the TiO 2. C Q 2 f, where Q is constant phase element (CPE), α is a constant, and f p is the peak frequency 1 of Nyquist impedance plots. c electron transport resistance, R ct (= r ct L) d interfacial charge recombination resistance, R r (= r r /L) p 6

8 e the average electron lifetime in TiO ' 2, C f the average electron transit time, τ d =L 2 /D e g electron diffusion coefficient, h electron mobility, e D e / k B T i electron diffusion length, L d =( τ n D e ) 0.5 j D charge collection efficiency S1-S3, e ' n R r 2 r / r L / 2 r ct n ( ( ) ( ) ) ( )( ) ( ), where α is the extinction coefficient of quantum dot-sensitized TiO 2 film. Here we assume theαl equals to 1 for the calculation. Another well-adopted formula for the charge collection efficiency is ( ). However, it is only valid when the cell active layer is thin enough so that the photo-generated electrons either immediately transport to the electrodes or recombine. In the case L=L d results in, indicating this formula obviously deviates the real situation of the quantum dot-sensitized solar cells. 7

9 Supplementary References S1. J. Halme, P. Vahermaa, K. Miettunen and P. Lund, Adv Mater, 10, 22, E S2. X. Dang, H. Yi, M. H. Ham, J. Qi, D. S. Yun, R. Ladewski, M. S. Strano, P. T. Hammond and A. M. Belcher, Nature nanotechnology, 11, 6, S3. L. Bertoluzzi, S. Ma, Physical chemistry chemical physics : PCCP, 13, 15,