Supporting Information Surface Modification of ZnO Nanorods with ...
Supporting Information
Surface Modification of ZnO Nanorods with Small Organic Molecular Dyes for Polymer–Inorganic Hybrid Solar Cells
Pipat Ruankham, Lea Macaraig, Takashi Sagawa,* Hiroyuki Nakazumi, and Susumu Yoshikawa*
*
To whom correspondence should be address. E-mail: [email protected], [email protected]
u.ac.jp Tel: +81-774-38-4580, Fax: +81-774-38-3508
S1
Contents
page 1. General
S3
2. Characterization of Sq dye
S4
3. Morphology of ZnO nanorods
S5
4. Absorbance and IPCE spectra of devices for various nanorod lengths
S6
5. Single diode model fitting
S7
6. Comparison of calculated Voc and measured Voc
S8
7. Dye adsorption condition
S9
S2
1.
General The indium tin oxide (ITO) (10 Ω sq–1) substrates were purchased from GEOMATEC Co., Ltd.
Hexamethylenetetramine, 2-methoxyethanol and poly(3-hexylthiophene) (P3HT) were purchased from Sigma-Aldrich Co. Zinc acetate, Zinc nitrate hexahydrate, and Monoethanolamine were purchased from Wako Pure Chemical Industries, Ltd. N719 or ruthenium(II) complex of cis (thiocyanate)- bis (bipyridinium) tert-butylammonium salt was purchased from Solaronix SA. D205 or 2-((E)-5-((1,2,3,3a,4,8b – hexahydro – 4 - (4 - (2,2 diphenylvinyl) phenyl) cyclopenta [b] indole-7-yl)methylene)-3-octyl-5-(3-carboxymethyl-4-oxothiazolidin-2-ylidene) rhodanine was purchased from Mitsubishi Paper Mills Ltd. NKX2677 or (2cyano-3-
[5’-(1,1,6,6-tetramethyl
-10-oxo-2,3,5,6-tetrahydro-1H,4H,10H-11-oxa-3a-azabenzo[de]
anthracen -9-yl)- [2,2’]bithiophenyl-5-yl]acrylic acid) was purchased from Hayashibara Biochemical Labs., Inc. The derivative of squaraine dye was synthesized as described in section 2.1 of the main article. The ITO/glass substrate was cleaned with a UV/ozone cleaner (UV-253) (Filgen, Inc.). Photocurrentvoltage characteristics were measured by using a CEP 2000 (BUNKOUKEIKI Co., Ltd.). The light intensity of the illumination source was adjusted by using a standard silicon photodiode (BS520) (BUNKOUKEIKI Co., Ltd.).
S3
2. 1
Characterization of Sq dye
H-NMR (400 MHz, DMSO-d6) δ 8.30 (s, 1H), 8.13 (s, 1H), 8.04 (m, 3H), 7.60 (d, 1H, J = 8.78 Hz),
6.85 (d, 2H, J = 7.81 Hz), 6.04 (s, 1H), 4.29 (q, 2H, J = 7.32 Hz), 3.47 (t, 2H, J = 7.08 Hz), 3.06 (s, 3H), 1.73 (s, 6H), 1.53 (quint., 2H, J = 7.69 Hz), 1.33 (m, 5H), 0.91 (t, 3H, J = 7.57 Hz); TOF-MS (m/z) 471 ([M-1]-, 100%);λ max (ε) (CHCl3): 641 nm(2.2×105 M-1cm-1); νmax/ cm-1 3436, 2939, 1564. Anal. Calcd for C29H32N2O4·H2O: C, 71.00; H, 6.99; N, 5.71. Found: C, 71.36; H, 6.91; N, 5.92.
S4
3.
Morphology of ZnO nanorods The length of ZnO nanorods was controlled by the duration of the hydrothermal growth. Note that the
0-min device is fabricated by coating P3HT on a dense layer of ZnO without nanorods. The crosssection and top views from FE-SEM measurement show inhomogeneous orientation of ZnO nanorods onto ITO substrate. a)
Nanorod 100 nm
Dense ZnO ITO Duration (min): 0
15
25
35
45
60
c)
b)
Figure S1. a) FE-SEM cross-section images of ZnO nanorods grown at 90oC for 0 – 60 min , b) the average length of nanorods versus duration growth, and c) top views of nanorods grown for 25 min.
S5
4.
Absorbance and IPCE spectra of devices for various nanorod lengths
Figure S2. a) UV-vis absorption spectra of ZnO nanorods/P3HT films, b) IPCE spectra of the devices structured ITO/ZnO nanorods/P3HT/Ag. The absorption peak at 370 nm increases as the length of ZnO nanorods were increased. The peak at 510 nm (P3HT peak) however did not vary significantly with the length of the ZnO nanorods. However, in the incident photon-to-current conversion efficiency (IPCE) spectra, the peak at 510 nm increased with the length of the nanorods. This indicate that the improvement of Jsc with respect to the length of the nanorods is due to the increased surface area for charge transfer and not the photogeneration properties of the material.
S6
5.
Single diode model fitting
The obtained photovoltaic properties for the devices were fitted using the single diode model summarized by Equation (S1);1
V − JRS A V − JRS A J = J 0 exp − J ph − 1 + RP A nkT / e
(S1)
where J is the current density, J0 is the diode reverse saturation current density, Jph is the light-generated current density, q is the electronic charge, V is the applied voltage, A is the device active area, RS is the series resistance, n is the ideality factor, k is Boltzmann’s constant, T is temperature, and RP is the shunt resistance. The fitting parameters were J0 and n. The J-V characteristics for all devices were fitted well as proven by Figure S3 and Table S1.
Figure S3. Experimental (shapes) and fitted (solid lines) JV characteristics of hybrid ZnO
nanorod/P3HT solar cells modified by a) N719, b)NKX2677, c)D205, and d) Sq dye. 1) Choi, S.; Potscavage, W. J.; Kippelen, B. J. Appl. Phys. 2009, 106, 054507. S7
6.
Comparison of calculated Voc and measured Voc
Table S1. Comparison of calculated Voc (Voc,cal)* and measured Voc (Voc,mea) at different length of
nanorod devices. No dye
N719
NKX2677
D205
Sq
Length of nanorods (nm)
Voc,cal
Voc,mea
Voc,cal
Voc,mea
Voc,cal
Voc,mea
Voc,cal
Voc,mea
Voc,cal
Voc,mea
(V)
(V)
(V)
(V)
(V)
(V)
(V)
(V)
(V)
(V)
0
0.154
0.177
0.225
0.241
0.501
0.535
0.559
0.585
0.295
0.338
125
0.330
0.377
0.331
0.339
0.430
0.444
0.624
0.632
0.372
0.390
185
0.427
0.451
0.314
0.321
0.497
0.510
0.653
0.662
0.418
0.418
288
0.443
0.466
0.303
0.310
0.435
0.465
0.483
0.503
0.428
0.433
455
0.243
0.250
0.318
0.325
0.406
0.331
0.348
0.352
0.416
0.420
571
0.178
0.181
0.273
0.281
0.224
0.231
0.257
0.260
0.381
0.386
* Voc,cal was evaluated from equation Voc =
J nkT ln( sc + 1) as described in main article. q J0
S8
7.
Dye adsorption condition
Adsorption conditions (variation of temperature and soaking time) for these dyes were investigated. The results are shown in Fig S4a)-b). Dye adsorption at 60oC for 60 min (in acetonitrile + t-butanol, 1:1) shows the optimum PCEs of the devices. Moreover, the solvent for the derivatized squaraine dye were compared. Ethanol, the common solvent for squaraine dyes, and acetonitrile + t-butanol (AN+TBA) were used. Figure S4c) shows no significantly different in PCEs for dye adsorption condition at various time and temperature. Note that the solvent system for the other dyes was no longer optimized since AN+TBA is already commonly used as shown in the literatures.2-5
Figure S4. Dye adsorption condition with variation of a) soaking temperature (soaking time 60 min),
b) soaking time (soaking temperature 60oC), and c) solvent system for the derivatized squaraine dye.
S9
(2) Pauporte, T.; Le Bahers, T.; Labat, F.; Ciofini, I. Phys Chem Chem Phys 2010, 12, 14710. (3) Wong, B. M.; Cordaro, J. G. J Chem Phys 2008, 129. (4) Chiu, W. H.; Lee, C. H.; Cheng, H. M.; Lin, H. F.; Liao, S. C.; Wu, J. M.; Hsieh, W. F. Energ Environ Sci 2009, 2, 694. (5) De Angelis, F.; Fantacci, S.; Selloni, A.; Gratzel, M.; Nazeeruddin, M. K. Nano Lett 2007, 7, 3189.
S10
Surface Modification of ZnO Nanorods with Small Organic Molecular Dyes for Polymer–Inorganic Hybrid Solar Cells
Pipat Ruankham, Lea Macaraig, Takashi Sagawa,* Hiroyuki Nakazumi, and Susumu Yoshikawa*
*
To whom correspondence should be address. E-mail: [email protected], [email protected]
u.ac.jp Tel: +81-774-38-4580, Fax: +81-774-38-3508
S1
Contents
page 1. General
S3
2. Characterization of Sq dye
S4
3. Morphology of ZnO nanorods
S5
4. Absorbance and IPCE spectra of devices for various nanorod lengths
S6
5. Single diode model fitting
S7
6. Comparison of calculated Voc and measured Voc
S8
7. Dye adsorption condition
S9
S2
1.
General The indium tin oxide (ITO) (10 Ω sq–1) substrates were purchased from GEOMATEC Co., Ltd.
Hexamethylenetetramine, 2-methoxyethanol and poly(3-hexylthiophene) (P3HT) were purchased from Sigma-Aldrich Co. Zinc acetate, Zinc nitrate hexahydrate, and Monoethanolamine were purchased from Wako Pure Chemical Industries, Ltd. N719 or ruthenium(II) complex of cis (thiocyanate)- bis (bipyridinium) tert-butylammonium salt was purchased from Solaronix SA. D205 or 2-((E)-5-((1,2,3,3a,4,8b – hexahydro – 4 - (4 - (2,2 diphenylvinyl) phenyl) cyclopenta [b] indole-7-yl)methylene)-3-octyl-5-(3-carboxymethyl-4-oxothiazolidin-2-ylidene) rhodanine was purchased from Mitsubishi Paper Mills Ltd. NKX2677 or (2cyano-3-
[5’-(1,1,6,6-tetramethyl
-10-oxo-2,3,5,6-tetrahydro-1H,4H,10H-11-oxa-3a-azabenzo[de]
anthracen -9-yl)- [2,2’]bithiophenyl-5-yl]acrylic acid) was purchased from Hayashibara Biochemical Labs., Inc. The derivative of squaraine dye was synthesized as described in section 2.1 of the main article. The ITO/glass substrate was cleaned with a UV/ozone cleaner (UV-253) (Filgen, Inc.). Photocurrentvoltage characteristics were measured by using a CEP 2000 (BUNKOUKEIKI Co., Ltd.). The light intensity of the illumination source was adjusted by using a standard silicon photodiode (BS520) (BUNKOUKEIKI Co., Ltd.).
S3
2. 1
Characterization of Sq dye
H-NMR (400 MHz, DMSO-d6) δ 8.30 (s, 1H), 8.13 (s, 1H), 8.04 (m, 3H), 7.60 (d, 1H, J = 8.78 Hz),
6.85 (d, 2H, J = 7.81 Hz), 6.04 (s, 1H), 4.29 (q, 2H, J = 7.32 Hz), 3.47 (t, 2H, J = 7.08 Hz), 3.06 (s, 3H), 1.73 (s, 6H), 1.53 (quint., 2H, J = 7.69 Hz), 1.33 (m, 5H), 0.91 (t, 3H, J = 7.57 Hz); TOF-MS (m/z) 471 ([M-1]-, 100%);λ max (ε) (CHCl3): 641 nm(2.2×105 M-1cm-1); νmax/ cm-1 3436, 2939, 1564. Anal. Calcd for C29H32N2O4·H2O: C, 71.00; H, 6.99; N, 5.71. Found: C, 71.36; H, 6.91; N, 5.92.
S4
3.
Morphology of ZnO nanorods The length of ZnO nanorods was controlled by the duration of the hydrothermal growth. Note that the
0-min device is fabricated by coating P3HT on a dense layer of ZnO without nanorods. The crosssection and top views from FE-SEM measurement show inhomogeneous orientation of ZnO nanorods onto ITO substrate. a)
Nanorod 100 nm
Dense ZnO ITO Duration (min): 0
15
25
35
45
60
c)
b)
Figure S1. a) FE-SEM cross-section images of ZnO nanorods grown at 90oC for 0 – 60 min , b) the average length of nanorods versus duration growth, and c) top views of nanorods grown for 25 min.
S5
4.
Absorbance and IPCE spectra of devices for various nanorod lengths
Figure S2. a) UV-vis absorption spectra of ZnO nanorods/P3HT films, b) IPCE spectra of the devices structured ITO/ZnO nanorods/P3HT/Ag. The absorption peak at 370 nm increases as the length of ZnO nanorods were increased. The peak at 510 nm (P3HT peak) however did not vary significantly with the length of the ZnO nanorods. However, in the incident photon-to-current conversion efficiency (IPCE) spectra, the peak at 510 nm increased with the length of the nanorods. This indicate that the improvement of Jsc with respect to the length of the nanorods is due to the increased surface area for charge transfer and not the photogeneration properties of the material.
S6
5.
Single diode model fitting
The obtained photovoltaic properties for the devices were fitted using the single diode model summarized by Equation (S1);1
V − JRS A V − JRS A J = J 0 exp − J ph − 1 + RP A nkT / e
(S1)
where J is the current density, J0 is the diode reverse saturation current density, Jph is the light-generated current density, q is the electronic charge, V is the applied voltage, A is the device active area, RS is the series resistance, n is the ideality factor, k is Boltzmann’s constant, T is temperature, and RP is the shunt resistance. The fitting parameters were J0 and n. The J-V characteristics for all devices were fitted well as proven by Figure S3 and Table S1.
Figure S3. Experimental (shapes) and fitted (solid lines) JV characteristics of hybrid ZnO
nanorod/P3HT solar cells modified by a) N719, b)NKX2677, c)D205, and d) Sq dye. 1) Choi, S.; Potscavage, W. J.; Kippelen, B. J. Appl. Phys. 2009, 106, 054507. S7
6.
Comparison of calculated Voc and measured Voc
Table S1. Comparison of calculated Voc (Voc,cal)* and measured Voc (Voc,mea) at different length of
nanorod devices. No dye
N719
NKX2677
D205
Sq
Length of nanorods (nm)
Voc,cal
Voc,mea
Voc,cal
Voc,mea
Voc,cal
Voc,mea
Voc,cal
Voc,mea
Voc,cal
Voc,mea
(V)
(V)
(V)
(V)
(V)
(V)
(V)
(V)
(V)
(V)
0
0.154
0.177
0.225
0.241
0.501
0.535
0.559
0.585
0.295
0.338
125
0.330
0.377
0.331
0.339
0.430
0.444
0.624
0.632
0.372
0.390
185
0.427
0.451
0.314
0.321
0.497
0.510
0.653
0.662
0.418
0.418
288
0.443
0.466
0.303
0.310
0.435
0.465
0.483
0.503
0.428
0.433
455
0.243
0.250
0.318
0.325
0.406
0.331
0.348
0.352
0.416
0.420
571
0.178
0.181
0.273
0.281
0.224
0.231
0.257
0.260
0.381
0.386
* Voc,cal was evaluated from equation Voc =
J nkT ln( sc + 1) as described in main article. q J0
S8
7.
Dye adsorption condition
Adsorption conditions (variation of temperature and soaking time) for these dyes were investigated. The results are shown in Fig S4a)-b). Dye adsorption at 60oC for 60 min (in acetonitrile + t-butanol, 1:1) shows the optimum PCEs of the devices. Moreover, the solvent for the derivatized squaraine dye were compared. Ethanol, the common solvent for squaraine dyes, and acetonitrile + t-butanol (AN+TBA) were used. Figure S4c) shows no significantly different in PCEs for dye adsorption condition at various time and temperature. Note that the solvent system for the other dyes was no longer optimized since AN+TBA is already commonly used as shown in the literatures.2-5
Figure S4. Dye adsorption condition with variation of a) soaking temperature (soaking time 60 min),
b) soaking time (soaking temperature 60oC), and c) solvent system for the derivatized squaraine dye.
S9
(2) Pauporte, T.; Le Bahers, T.; Labat, F.; Ciofini, I. Phys Chem Chem Phys 2010, 12, 14710. (3) Wong, B. M.; Cordaro, J. G. J Chem Phys 2008, 129. (4) Chiu, W. H.; Lee, C. H.; Cheng, H. M.; Lin, H. F.; Liao, S. C.; Wu, J. M.; Hsieh, W. F. Energ Environ Sci 2009, 2, 694. (5) De Angelis, F.; Fantacci, S.; Selloni, A.; Gratzel, M.; Nazeeruddin, M. K. Nano Lett 2007, 7, 3189.
S10
