Supporting Information

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1 Supporting Information Molecular Engineering of Triphenylamine-Based Non-fullerene Electron Transport Materials for Efficient Rigid and Flexible Perovskite Solar Cells Cheng Chen, a # Hongping Li, a # Xingdong Ding, a Ming Cheng, a * Henan Li, c Li Xu, a Fen Qiao, d Huaming Li, a Licheng Sun b * a Institute for Energy Research, Jiangsu University, Zhenjiang , P. R. China * mingcheng@ujs.edu.cn. b Department of Chemistry, KTH Royal Institute of Technology, SE Stockholm, Sweden * lichengs@kth.se c School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang , P. R. China d School of Energy and Power Engineering, Jiangsu University, Zhenjiang , P. R. China # These two authors contribute equally. S1

2 1. Materials and Instruments Starting materials for ETM synthesis, N, N-dimethylformamide (DMF), dimethyl sulphoxide (DMS) and chlorobenzene (CB) were all purchased from were purchased from Energy Chemical. PbI 2, methylammonium iodide (MAI), PC 61 BM and Bathocuproine (BCP) were purchased from Xi an Polymer Light Technology Corp, 4,4',4''- nitrilotribenzaldehyde was purchased from Sigma-Aldrich, 2-(3-cyano-4,5,5- trimethylfuran-2(5h)-ylidene) malononitrile was purchased from Alfa Aesar. All the chemicals were directly used without further purification. 1 H-NMR, 13 C NMR spectrum was performed on a Varian INVA 400M NMR apparatus. Chemical shifts were calibrated against TMS as an internal standard. The UV-vis spectra were recorded by an Agilent 8453 spectrophotometer. The steady-state photoluminescence spectra were recorded on a Varian Cary Eclipse fluorescence spectrophotometer. Timeresolved photoluminescence decay spectra were carried out with a LP920 laser flash spectrometer (Edinburgh Instruments). Cyclic voltammetry (CV) was performed in dichloromethane with 0.1 M TBAPF 6 as the supporting electrolyte, an Ag + /AgN 3 electrode as the reference electrode, a carbon-glass electrode as the working electrode, a Pt electrode as the counter electrode and ferrocene/ferrocenium (Fc/Fc + ) as an internal reference with a CH instruments electrochemical workstation (model 660 A). The SEM images were taken on a JEL JSM-S4800. Light source for the photocurrent-voltage (J V) measurement is an AM 1.5G solar simulator. The incident light intensity was 100 S2

3 mw cm -2 calibrated with a standard Si solar cell. The tested solar cells were masked to a working area of 0.09 cm 2. The photocurrent-voltage (J V) curves were obtained by the linear sweep voltammetry (LSV) method using a Keithley 2400 source-measure unit with scan rate of 20 mv s -1. The measurement of the incident-photon-to-current conversion efficiency (IPCE) was performed with a Xenon arc lamp (300 W), a 1/8 m monochromator, a source/meter, and a power meter with a 818-UV detector head. Electron mobility was measured by using the space-charge-limited current (SCLC) method with the device structure of FT/Ti 2 /ETM/Ti 2 /Ag. The electrical conductivities of the ETM were determined by using two-probe electrical conductivity measurements according to our previous reports. 2. Perovskite Solar Cell Fabrication Conducting FT glass or IT-polyethylene terephthalate (PET) substrates were cut (25 mm x 25 mm) and patterned by chemical etching using zinc powder and hydrochloric acid. The substrates were washed by sonication subsequentially in deionized water, acetone and ethanol for 15 minutes each. For rigid devices, a thin and dense layer of Ni was applied on the glass using spray-pyrolysis at 450 C from a solution of 0.02 M nickel acetylacetonate in acetonitrile : ehhanol mixed solvent (volume ratio = 95 : 5). The samples were further sintered at 450 C for 30 minutes. For flexible devices, the PEDT:PSS layer was fabricated by spin-coating PEDT:PSS solution at 2000 rpm for 60 seconds. The following steps expect evaporation were performed in an N 2 glovebox. To yield a MAPbI 3 S3

4 perovskite solution we mixed PbI 2 and MAI in molar concentrations of 1.16 and 1.1, respectively, in 4:1 DMF:DMS. The solutions were stirred to dissolve the inorganic salts at room temperature. The prepared substrates were placed on the spin-coater and 75 µl of the perovskite solution spread onto the Ni/PEDT:PSS film. The substrate was the spincoated at 1000 rpm for 10 seconds and 5000 rpm for 30 seconds with a ramp speed of 2000 rpm/s. During the second spin-coating step an anti-solvent was injected onto the film after 15 seconds using 200 µl of chlorobenzene. The perovskite films were then annealed at 100 C for 30 minutes on a hotplate. Subsequently, the ETL was deposited on perovskite surface by spin coating ETM solution (20 mg TPA-3 with or without 0.03% wt H2 dissolved in chlorobenzene) at 1800 rpm for 30 s. Then, 3nm BCP and a layer of 200 nm Al was deposited sequentially under high vacuum (< Pa) by thermal evaporation through a shadow mask to form an active area of 20 mm Synthesis of ETM TPA-3 HC N CH CH + Et 3 N, CHCl 3 reflux N TPA-3 Scheme S1. The synthetic route of non-fullerene ETM TPA-3 4,4',4''-nitrilotribenzaldehyde (987 mg, 3 mmol), 2-(3-cyano-4,5,5-trimethylfuran-2(5H)- ylidene) malononitrile (716 mg, 3.6 mmol) and five drops triethylamine were added to S4

5 anhydrous CHCl 3 (50 ml). After the mixture was refluxed for 24 h, the solution was extracted with dichloromethane and 0.1 M HCl aqueous solution. The organic phase was dried over anhydrous MgS 4 and the solvent was removed in vacuo. The crude product was purified by column chromatography (CH 2 Cl 2 : petroleum ether) to give TPA-3 as purple solid (1.78 g, 75%). 1 H NMR (400 MHz, Acetone) δ 8.05 (d, J = 16.4 Hz, 3H), 7.96 (t, J = 7.0 Hz, 6H), 7.31 (dd, J = 16.3, 8.5 Hz, 9H), 1.93 (s, 18H). 13 C NMR (400 MHz, Acetone) δ , , , , , , , , , , , , 99.28, 98.78, 55.45, 54.10, 29.01, HRMS calculated: C 54 H 36 N 10 3, , found: Cost estimation The cost estimation was done according to previously published material cost model. [1] The prices of all materials used for the synthesis of TPA-3 have been taken from Sigma- Aldrich and Alfa Aesar websites. The synthetic flow charts and material cost calculations can be found below. The results are summarized in Table S1. Reaction CHCl 3 : 50 ml triethylamine: 0.1 g Extraction CH 2 Cl 2 : 100 ml Column chromatography CH 2 Cl 2 1L petroleum ether 500 ml HC CH N + CH 987 mg 716 mg 68% solvent reagants workup material N TPA g S5

6 Table S1 Estimated materials cost for the synthesis of TPA-3 Chemical name Price of Chemical Material cost($/g product) nitrilotribenzaldehyde 134 $/g ,4',4''- 2-(3-cyano-4,5,5- trimethylfuran-2(5h)- 45 $/g ylidene) malononitrile CHCl $/kg 0.19 triethylamine $/kg CH 2 Cl $/kg petroleum ether $/kg 5.58 Silica $/kg Total S6

7 Figure S1 1HNMR and 13MR of ETM TPA-3 Figure S2. a) Current-voltage characteristics of TPA-3 based electron-only devices and b) Electron conductivity of TPA-3 with different n-type dopant concentrations S7

8 Figure S3 Photovoltaic performance of PC 61 BM based PSC Figure S4. Statistics of photovoltaic parameters V oc (a), J sc (b), FF (c), and PCE (d) of PSCs containing pristine and doped TPA-3 as ETMs measured under AM 1.5 G illumination S8

9 (100 mw cm 2 ) Figure S5. Aging test results [a) V oc, b) J sc, c) FF and d) PCE] of pristine TPA- 3, doped TPA-3 and PC 61 BM based PSCs Figure S6. Water contact angle of pristine TPA-3 and doped TPA-3 film S9