Fluorinated Benzothiadiazole Based Conjugated Polymers for High ...
Supporting Information
Fluorinated Benzothiadiazole Based Conjugated Polymers for High-Performance Polymer Solar Cells without Any Processing Additives or Post Treatments Ning Wang,‡ Zheng Chen,*,† Wei Wei,† and Zhenhua Jiang† †
Alan G. MacDiarmid Lab, College of Chemistry, Jilin University, Xiuzheng Road 1788,
Changchun 130012, People’s Republic of China ‡
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied
Chemistry, Chinese Academy of Sciences, Renmin Str. 5625, Changchun 130022, People’s Republic of China
To whom correspondence should be addressed. Email: [email protected]
Synthetic Details Methods and Materials: All reagents from commercial sources were used without further purification, unless otherwise noted. All reactions were performed under dry N2 or Ar, unless otherwise noted. All dry reactions were performed with glassware that was oven dried and then flamed under high-vacuum and backfilled with N2. All extracts were dried over powdered MgSO4 and solvents removed by rotary evaporation under reduced pressure. Flash chromatography was performed using Qingdao Haiyang HG/T2354-92 (300-400 mesh) silica. Chlorobenzene (CB, anhydrous, 99+ %) and 1,8-diiodoctane (DIO) were purchased from Sigma-Aldrich Company. PC71BM and PC61BM was purchased from Alfa Aesar. All small molecules were characterized by 1H NMR and
13
C NMR on a Bruker
AVB-4001HNMR spectra in CDCl3 (1H, δ: 7.26 ppm ； 13C, δ: 77 ppm) with trimethylsilane (TMS) as the internal standard. The number-average molecular weight (Mn) was determined by gel permeation chromatography (GPC) using 1, 2, S1
4-trichlorobenzene as eluent at 120 oC with a PL-GPC 220 instruments. The obtained molecular weight is calibrated with the polystyrene standard. Thermogravimetric analysis (TGA) was investigated using a METTLER TOLEDO TGA 1100 LF apparatus operated at a heating rate of 10 ℃/ min under a N2 atmosphere. UV-Vis absorption spectra were taken on a Shimadzu UV-2510 spectrometer. The structural property of polymer was determined by X-ray diffraction measurements (XRD: Siemens D5005 X-Ray Diffractometer). The thickness of the functional layers were measured using a Dektak profilometer (Ambios. Technology. Inc. XP2).Current density-voltage (J-V) characteristics were measured by a Keithley model 236 digital source-meter exposing the cell to class AAA Newport Air Mass 1.5 Global (AM 1.5G) full spectrum solar simulator. The incident light intensity was set at 100 mWcm-2 using a NREL calibrated silicon solar cell. IPCE measurements were performed under short-circuit conditions with a lock-amplifier (Stanford Research System, Inc, SR830) at a chopping frequency of 280 Hz during illumination with a monochromatic light form a 150 W Xenon lamp. The morphology and surface roughness of the layers were determined by atomic-force microscopy (AFM, Digital Instruments Nano Scope III).
Electrochemical
Cyclic
Voltammetry
Measurement:
Cyclic
voltammetry
measurements were performed on a CHI 610D electrochemical workstation with a three-electrode system in a solution of 0.1 MBu4NPF6 in anhydrous acetonitrile at a scan rate of 50 mVs-1. The polymer films were coated on a glassy carbon electrode (1.0 cm2) by dipping the electrode into the corresponding solutions and then drying. A platinum wire was used as the counter electrode, and a silver wire was used as a quasi-reference electrode. The potential of the as-prepared polymer was corrected by the standard reference of Fc/Fc+ in CH3CN (0.44 V vs Ag/Ag+ electrode), where the absolute energy level of ferrocene is −4.8 eV below the vacuum level. The HOMO and LUMO energy levels of the polymer were calculated according to the equation: EHOMO = − (Eonset ox + 4.36) eV
(1)
ELUMO = − (Eonset + 4.36) eV red
(2)
in which Eonset and Eonset are the onset potentials for the oxidation and reduction ox red S2
processes, respectively. Hole-only Device Fabrication and Measurement： ：The hole mobility were carried out using the space charge limited current method (SCLC), employing a device architecture of ITO/PEDOT:PSS/polymer or polymer:PC71BM/Au and taking current-voltage measurements in the range of 0-13 V and fitting the results to a space charge limited form, where the SCLC is described by J 8/9 /
(3)
Where the permittivity of free space, is the dielectric constant of the polymer, is thehole mobility, is the voltage drop across the device ( , where is theapplied voltage to the device, is the voltage drop due to contact resistance and seriesresistance across the electrodes, and is the built-in voltage due to the difference in workfunction of the two electrodes), L is the thickness of polymer. The dielectric constant is assumed to be 3, which is a typical value for conjugated polymers. Device Fabrication and Measurement Patterned ITO-glass substrates were used as the anode in polymer solar cells. ITO substrates were first pre-cleaned sequentially by sonicating in a detergent bath, de-ionized water, acetone, and isopropanol, and in a boiled isopropanol bath each for 20 min, and then dried in an oven for 3 h, which were then subjected to a UV/ozone treatment for 30 min. A thin layer (~30 nm) of PEDOT: PSS (Baytron P VP A1 4083) was spin-coated onto the ITO surface. After being baked at 140 °C for 25 min in ambient air, the substrates were transferred into a nitrogen-filled glove box (
Fluorinated Benzothiadiazole Based Conjugated Polymers for High-Performance Polymer Solar Cells without Any Processing Additives or Post Treatments Ning Wang,‡ Zheng Chen,*,† Wei Wei,† and Zhenhua Jiang† †
Alan G. MacDiarmid Lab, College of Chemistry, Jilin University, Xiuzheng Road 1788,
Changchun 130012, People’s Republic of China ‡
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied
Chemistry, Chinese Academy of Sciences, Renmin Str. 5625, Changchun 130022, People’s Republic of China
To whom correspondence should be addressed. Email: [email protected]
Synthetic Details Methods and Materials: All reagents from commercial sources were used without further purification, unless otherwise noted. All reactions were performed under dry N2 or Ar, unless otherwise noted. All dry reactions were performed with glassware that was oven dried and then flamed under high-vacuum and backfilled with N2. All extracts were dried over powdered MgSO4 and solvents removed by rotary evaporation under reduced pressure. Flash chromatography was performed using Qingdao Haiyang HG/T2354-92 (300-400 mesh) silica. Chlorobenzene (CB, anhydrous, 99+ %) and 1,8-diiodoctane (DIO) were purchased from Sigma-Aldrich Company. PC71BM and PC61BM was purchased from Alfa Aesar. All small molecules were characterized by 1H NMR and
13
C NMR on a Bruker
AVB-4001HNMR spectra in CDCl3 (1H, δ: 7.26 ppm ； 13C, δ: 77 ppm) with trimethylsilane (TMS) as the internal standard. The number-average molecular weight (Mn) was determined by gel permeation chromatography (GPC) using 1, 2, S1
4-trichlorobenzene as eluent at 120 oC with a PL-GPC 220 instruments. The obtained molecular weight is calibrated with the polystyrene standard. Thermogravimetric analysis (TGA) was investigated using a METTLER TOLEDO TGA 1100 LF apparatus operated at a heating rate of 10 ℃/ min under a N2 atmosphere. UV-Vis absorption spectra were taken on a Shimadzu UV-2510 spectrometer. The structural property of polymer was determined by X-ray diffraction measurements (XRD: Siemens D5005 X-Ray Diffractometer). The thickness of the functional layers were measured using a Dektak profilometer (Ambios. Technology. Inc. XP2).Current density-voltage (J-V) characteristics were measured by a Keithley model 236 digital source-meter exposing the cell to class AAA Newport Air Mass 1.5 Global (AM 1.5G) full spectrum solar simulator. The incident light intensity was set at 100 mWcm-2 using a NREL calibrated silicon solar cell. IPCE measurements were performed under short-circuit conditions with a lock-amplifier (Stanford Research System, Inc, SR830) at a chopping frequency of 280 Hz during illumination with a monochromatic light form a 150 W Xenon lamp. The morphology and surface roughness of the layers were determined by atomic-force microscopy (AFM, Digital Instruments Nano Scope III).
Electrochemical
Cyclic
Voltammetry
Measurement:
Cyclic
voltammetry
measurements were performed on a CHI 610D electrochemical workstation with a three-electrode system in a solution of 0.1 MBu4NPF6 in anhydrous acetonitrile at a scan rate of 50 mVs-1. The polymer films were coated on a glassy carbon electrode (1.0 cm2) by dipping the electrode into the corresponding solutions and then drying. A platinum wire was used as the counter electrode, and a silver wire was used as a quasi-reference electrode. The potential of the as-prepared polymer was corrected by the standard reference of Fc/Fc+ in CH3CN (0.44 V vs Ag/Ag+ electrode), where the absolute energy level of ferrocene is −4.8 eV below the vacuum level. The HOMO and LUMO energy levels of the polymer were calculated according to the equation: EHOMO = − (Eonset ox + 4.36) eV
(1)
ELUMO = − (Eonset + 4.36) eV red
(2)
in which Eonset and Eonset are the onset potentials for the oxidation and reduction ox red S2
processes, respectively. Hole-only Device Fabrication and Measurement： ：The hole mobility were carried out using the space charge limited current method (SCLC), employing a device architecture of ITO/PEDOT:PSS/polymer or polymer:PC71BM/Au and taking current-voltage measurements in the range of 0-13 V and fitting the results to a space charge limited form, where the SCLC is described by J 8/9 /
(3)
Where the permittivity of free space, is the dielectric constant of the polymer, is thehole mobility, is the voltage drop across the device ( , where is theapplied voltage to the device, is the voltage drop due to contact resistance and seriesresistance across the electrodes, and is the built-in voltage due to the difference in workfunction of the two electrodes), L is the thickness of polymer. The dielectric constant is assumed to be 3, which is a typical value for conjugated polymers. Device Fabrication and Measurement Patterned ITO-glass substrates were used as the anode in polymer solar cells. ITO substrates were first pre-cleaned sequentially by sonicating in a detergent bath, de-ionized water, acetone, and isopropanol, and in a boiled isopropanol bath each for 20 min, and then dried in an oven for 3 h, which were then subjected to a UV/ozone treatment for 30 min. A thin layer (~30 nm) of PEDOT: PSS (Baytron P VP A1 4083) was spin-coated onto the ITO surface. After being baked at 140 °C for 25 min in ambient air, the substrates were transferred into a nitrogen-filled glove box (
