Supporting Information

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Scarlett Shaw
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1 Supporting Information High Efficiency Colloidal Quantum Dot Photovoltaics via Robust Self- Assembled Monolayers Gi-Hwan Kim,,, F. Pelayo García de Arquer,, Yung Jin Yoon, Xinzheng Lan, Men gxia Liu, Oleksandr Voznyy, Zhenyu Yang, Fengjia Fan, Alexander H. Ip, Pongsak orn Kanjanaboos, Sjoerd Hoogland, Jin Young Kim *,, Edward H. Sargent *, Department of Electrical and Computer Engineering, University of Toronto, 10 King s College Road, Toronto, Ontario, M5S 3G4, Canada School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) Ulsan , South Korea Indicates equal contribution ted.sargent@utoronto.ca, jykim@unist.ac.kr

2 a ZnO b ZnO/ABA c ZnO/NBA d ZnO e ZnO/ABA f ZnO/NBA Figure S1. Assessing the formation of the R-SAM: Survey of X-ray photoemission spectroscopy (XPS) spectra for (a) ZnO, ZnO with (b) ABA and, (c) NBA. Short range for N1s peak region around 400 nm (d) ZnO, ZnO with (e) ABA and, (f) NBA. The presence of nitrogen species confirms the incorporation of the R-SAM.

3 a. b. ZnO/ABA after Octane and MeOH washing ZnO/NBA after Octane and MeOH washing c. d. ZnO/ABA after Octane and MeOH washing ZnO/NBA after Octane and MeOH washing Figure S2. Assessing the formation of the R-SAM: Survey of XPS spectra for ZnO with (a) ABA (b) NBA after octane and 2 times methanol solution washing. To observe the presence of R-SAM layer on ZnO, short range for N peak region around 400 ev and 407 ev for NO x, after octane solution washing for (c) ABA (d) NBA respectively.

4 Figure S3. Changed surface property of ZnO with R-SAM: Contact angle measurements of (a) ZnO, with (b) ABA layer at 0.001% concentration, (c) ABA layer at 0.01% concentration, (d) ABA layer at 0.1% concentration, (e) NBA layer at 0.001% concentration, (f) NBA layer at 0.01% concentration, (g) NBA layer at 0.1% concentration. (h) Contact angle as function of ABA/NBA concentration on ZnO substrates.

5 a ZnO ZnO/ABA 0.1% ZnO/ABA 0.01% ZnO/ABA 0.001% b ZnO ZnO/NBA 0.1% ZnO/NBA 0.01% ZnO/NBA 0.001% Figure S4. UPS data for R-SAMs: Ultraviolet photoemission spectroscopy (UPS) spectra of ZnO and ZnO with (a) ABA with various concentration from 0.1% to 0.001% (b) NBA with various concentrations from 0.1% to 0.001% films, plotted relative to an Au reference.

6 Figure S5 Simulation of performance for CQD photovoltaic: Photovoltaic figures of merit as calculated from SCAPS as a function of exciton energy and induced dipole shift. (a) Open circuit-voltage, (b) fill factor, (c) short circuit-current, and (d) power conversion efficiency. The obtained trends are in good agreement with experimental results for both 1.4 ev and 1.3 ev CQDs.

7 25 20 w/o ABA w/ ABA Figure S6 Device hysteresis of devices with ABA layer (0.01% concentration) and without. J-V characteristics of CQD photovoltaics forward and revers scan with 0.01% ABA layer Voltage (V)

8 12 PCE (%) w/o ABA w/ ABA Days Figure S7 Device stability with ABA layer (0.01% concentration) and without. PCE stability in air stored condition.

9 a 25 b 25 Current Density(mA cm -2 ) ZnO ZnO/ABA 0.1% 5 ZnO/ABA 0.01% ZnO/ABA 0.001% Voltage (V) Current Density(mA cm -2 ) ZnO ZnO/NBA 0.1% 5 ZnO/NBA 0.01% ZnO/NBA 0.001% Voltage (V) Figure S8 CQD Photovoltaic characteristics: J-V characteristics of 1.4 ev CQD photovoltaic devices with different concentration of (a) ABA and (b) NBA R-SAM layer.

10 25 20 ZnO ZnO/ABA 0.01% ZnO ZnO/ABA PCE(%): J SC (ma cm -2 ): V OC (V): FF: Voltage (V) Figure S9 CQD Photovoltaic characteristics with small bandgap PbS: J-V characteristics of CQD photovoltaics using 950 nm PbS CQD with 0.01% ABA layer

11 Number of Devices Spin-coating with ABA in Air Dip-coating with ABA in Air Dip-coating with ABA in N2 Gauss fit for Spin-coating with ABA in Air Gauss fit for Dip-coating with ABA in Air Gauss fit for Dip-coating with ABA in N PCE (%) Figure S10 PCE histogram of devices with ABA layer (0.01% concentration) at various fabrication conditions, comparing the reproducibility and robustness of the R-SAM under device fabrication conditions. Spin-coating under air atmosphere results in a wide spread of PCE around 9.6 %. This is attributed to a non-homogeneous SAM and the influence of moisture during molecule adsorption. The use of dip-coating results in a higher and more uniform PCE. Both PCE and homogeneity are significantly improved by performing the assembly under inert atmosphere.

12 Table S1. Details of SCAPS simulation used parameters. The TBAI layer consists of a linear grading combination of the between the parameters listed and those of the EDT. The CQD band-edge for a given exciton peak was calculated from the absorption edge of the exciton peak. EDT layer TBAI layer ZnO layer Thickness (nm) Bandgap edge (ev) Electron affinity (ev) Permittivity (er) CB/VB DOS (cm -3 ) 1E19 1E19 1E19 Electron mobility (cm 2 /Vs) 2E-4 2E-2 5E-2 Ndonor (cm -3 ) 1E14 1E15 1E17 Nacceptor (cm -3 ) 1E16 1E15 0 EDT/TBAI defect (neutral) Capture cross section (cm2) 1.2E E-13 Position below Ec (ev) Density (cm-3) 1E16 1E16 TBAI-ZnO interface defects (neutral) Capture cross section (cm 2 ) 1E-19 Position above Ev (ev) 0.6 Density (cm -3 ) 1E16

13 Table S2. Device characteristics of CQD photovoltaics with various concentration ABA layer. Structure J SC (ma cm -2 ) V OC (V) FF PCE (%) ITO/ZnO/PbS/Au ITO/ZnO/ABA0.1%/PbS/Au ITO/ZnO/ ABA0.01%/PbS/Au ITO/ZnO/ ABA0.001%/PbS/Au

14 Table S3. Device characteristics of CQD photovoltaics with various concentration NBA layer. Structure J SC (ma cm -2 ) V OC (V) FF PCE (%) ITO/ZnO/PbS/Au ITO/ZnO/NBA0.1%/PbS/Au ITO/ZnO/ NBA0.01%/PbS/Au ITO/ZnO/ NBA0.001%/PbS/Au

Supplementary Fig. 1 Atomic force microscopy topography images Two-dimensional atomic force microscopy images (with an area of 1 m 1 m) of Cu and

Supplementary Fig. 1 Atomic force microscopy topography images Two-dimensional atomic force microscopy images (with an area of 1 m 1 m) of Cu and Cu(O = 5.0%) films deposited on 20-nm-thick ZnO films during