Performance improvement of RuII complexes pyridinyl backbone on dye-sensitized solar cells (DSSC)

Article abstract of DOI:10.1016/j.ica.2018.01.021

Two new series of Ru^II complexes (6–10 bearing an imine bond and 16–20 bearing a sulfonamidate fragment) based 8-aminoquinoline backbone were prepared and characterized by NMR, FT-IR, elemental analysis, UV–vis, CV etc. and tested as a photoact

Full text of DOI:10.1016/j.ica.2018.01.021

Accepted Manuscript
Research paper
Performance improvement of RuII Complexes Pyridinyl Backbone on Dye-Sen-
sitized Solar Cells (DSSC)
Serkan Dayan, Nilgün Kalaycıoğlu Özpozan
PII:
S0020-1693(17)31849-2
https://doi.org/10.1016/j.ica.2018.01.021
ICA 18095
DOI:
Reference:
Inorganica Chimica Acta
To appear in:
Received Date:
Revised Date:
Accepted Date:
4 December 2017
15 January 2018
19 January 2018
Please cite this article as: S. Dayan, N.K. Özpozan, Performance improvement of RuII Complexes Pyridinyl
Backbone on Dye-Sensitized Solar Cells (DSSC), Inorganica Chimica Acta (2018), doi: https://doi.org/10.1016/
j.ica.2018.01.021
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Performance improvement of RuII Complexes Pyridinyl Backbone on Dye-
Sensitized Solar Cells (DSSC)
Serkan Dayan, Nilgün Kalaycıoğlu Özpozan*
Department of Chemistry, Faculty of Science, Erciyes University, 38039 Kayseri, Turkey
*Corresponding authors; Tel: +90 505 644 11 70 and +90 506 277 21 75, Fax: +90 352 437
49 33
E-mail address: nozpozan@erciyes.edu.tr
Postal address: Department of Chemistry, Faculty of Science, Erciyes University, Kayseri,
38039, Turkey
Abstract
Two new series of RuII complexes (6-10 bearing an imine bond and 16-20 bearing a
sulfonamidate fragment) based 8-aminoquinoline backbone were prepared and characterized
by NMR, FT-IR, elemental analysis, UV-vis, CV etc. and tested as a photoactive dye for dye-
sensitized solar cells (DSSC).
The performance of the RuII-arene containing imine bond complex types (6-10) as a dye on
DSSCs produced cells with power conversion efficiencies (PCEs) of around 0.03 – 0.10%.
The [(N-Quinoline-8-yl-benzenesulfonamido)(p-cymene)chlororuthenium(II)] (SD-E1311)
complex, which we previously produced was tested instead of the complexes bearing the
imine bond (6-10) and its PCE for SD-E1311 was found as 0.12%. Herein, the increase of the
Voc is quite interesting and, for this reason, the sulfonamidate based complexes were selected
for the backbone structure.
To enhance immobilization to the titanium oxide layer and solubility and electron injection of
the corresponding excited dye on the DSSC process, 2,2'-bipyridine-4,4'-dicarboxylic acid as
the anchor group and thiocyanate ligands were selected instead of p-cymene and chloro
ligands over the sulfonamidate complex. Then, the photoactive dye properties of the new RuII
complexes (16-20) were investigated and the results showed that the 16-20 dyes bearing
sulfonamidate, carboxylic anchoring and thiocyanate fragments benefited the short-circuit
current and the open-circuit voltage, and had PCEs of 1.26%, 1.08%, 1.58%, 0.90% and
1.36% under AM1.5G irradiation, respectively. The working devices, results also show that
1

the 16-20 dyes demonstrated average performances with a PCEmax. of 1.58% which was
occurred with 18 complex.
Keywords: Ruthenium dye, DSSC, Sulfonamide, Solar Cell, Schiff Base
1. INTRODUCTION
Dye-sensitized solar cells (DSSCs) based on photoactive dye are well-regarded as one of the
promising new generations of photovoltaic devices on account of their environment-friendly,
low fabrication cost and good efficiency [1]. A typical DSSC is normally obtained by means
of a photoanode impregnated with dye, a counter electrode (CE) and liquid or solid electrolyte
-
containing redox species in the hole of the electrodes [2]. Iodide/triiodide (I-/I3 ) is most
preferred redox couple for electrolyte on DSSCs. The photon-to-electricity evolution of a
DSSC comprises some important steps. A photon particle absorbed by a sensitizer molecule
could be stimulated the progression of an electron particle (e-) from the highest occupied
molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) of the
corresponding molecular structure, when the photon energy is equivalent to or higher than the
bandgap between the HOMO and LUMO. The electron on the LUMO of the sensitizer
delivers to the conduction band of the photoanode (TiO2) electrode and transport along the
photoanode layer to the external circuit. The dye regeneration process by earning an e- from
-
iodide, 2dye+ + 3I- ꢀ 2dye0 + I3 . The redox species in the electrolyte transport and regenerate
-
by the CE as a result of the reduction of triiodide, with the I3 + 2e- ꢀ 3I- reaction. The
corresponding steps can be significantly affected by the PCE of working devices [3].
Notedly in the last decade, adjunct functionalizations have been attempted on photoactive
dyes, including a photoanode layer (TiO2), CEs and a liquid or solid electrolyte combination
in order to develop the general effectively of DSSCs [4-8] In fact, photoactive dyes are
critical to the success of this methodology as the PCE of the working device is known to be
widely affected by the raybeam and e- injection mechanisms of the excited dye. A wide
variety of dyes have been used in the DSSCs including metal free molecular structure based
dyes [9-12], Zn-porphyrin structures [13-15] and RuII-based photosensitizers [16, 17].
Although the high PCEs were achieved with organic backbone sensitizers (nearing 10%) [18,
19] and with porphyrin based dyes in combination with Co based redox couple (13%) [20-22]
2

and ruthenium(II) bearing polypyridyl dyes continue to be exhaustively investigated. Apart
from organic/inorganic molecule structure dyes, new hybrid materials with a perovskite
structure (MAPbI3, where MA = methylammonium or other derivatives) have demonstrated
16 – 19% PCE in solid state working devices [23-25]. However, health or environmental
hazards due to the fact that perovskites contain Pb, are still an important issue that may
adversely affect their future existence and therefore researchers are encouraged to use
conventional DSSCs.
Coordination compounds of the general structure ML2X2, where M= OsII or RuII, L stands for
2,2'-dicarboxybipyridine (dcbpy), X represents a halide, cyanide, thiocyanate, acetyl
acetonate, or thiocarbamate, and have been found to be efficient sensitizers. Ru-complexes
based on carboxy bpy or carboxy terpy such as N3 (11.03%), N719 (11.18%), Z907 (9.5%)
and [Bu4N]3[Ru(tctpy)(NCS)3] (black dye) are used worldwide as benchmark reference dyes
[26].
Regarding their stability in solar cell devices, the reference dyes have demonstrated a similar
character when compared to other Ru-bipyridyl sensitizers [27]. In particular, RuII sensitizers
bearing a thiocyanate fragment with the effect of the sulfur group make intimate contact in the
liquid electrolyte via the iodine redox couple that helps in the regeneration mechanism of the
sensitizer molecules [28]. However, the thiocyanate ligands are weakly coordinated to the Ru-
center and can be easily substituted by electrolyte additives, such as tert-butyl pyridine, or
solvent molecules due to thermal or light soaking reasons [29-31]. Moreover, very positive
results about PCE obtained with thiocyanate free Ru senstitizers [32-35].
Herein, we designed and fabricated a new series of ruthenium(II) complexes based on an 8-
aminoquinoline backbone. The design steps of the complexes are shaped according to the
properties of the sensitizer. We have tried to advance the sensitizer performance of working
devices with the addition of new groups, ligands and a backbone structure due to the Ru(II)
complexes bearing an imine bond having easy hydrolysis, lowered dye regeneration and
electron injection process. As a result, the performance improved Ru(II) sensitizers (16-20)
were tested and showed modest performances with a PCE of 0.90% - 1.58%.
3

2. EXPERIMENTAL
2.1. Synthesis of compounds
2.1.1. Synthesis procedure of Schiff Base Ligands and RuII complexes
Stage-1: Under an open atmosphere, a mixture of 8-aminoquinoline and aromatic aldehydes
was stirred in methanol at ambient temperature for 12 h. At the end of this time, the reaction
o
o
mixture was stirred at 50 C for an additional 1 h. After cooling to 0 C temperature, the
resulting suspension was filtered and washed with cooled methyl alcohol (3 x 5 ml). The pure
product (1-5) was dried under reduced atmosphere (Fig-1).
Stage-2: To a solution of 1-5 in methyl alcohol (5 ml) was added [RuCl2(p-cymene)]2 dimer
at ambient temperature in a Schlenk tube for 1 h. Then, the mixture was stirred at 50 oC for an
additional 12 h and cooled to ambient temperature. The volatiles were removed under vacuum
and recrystallized in an MeOH/diethyl ether (1:3) solvent mixture. The micro crystalline
product was collected by filtration and washed with a large quantity of diethyl ether and dried
in vacuo (Fig-1).
INSERT FIGURE-1
2.1.1.1. Data for N-3,4,5-trimethoxybenzylidenequinoline-8-amine (1)
1
Color: Yellow. Yield: 68 %. H-NMR (CDCl3, δ ppm): 3.92 (s, 6H, 3,5-OCH3), 3.94 (s,
3H, 4-OCH3), 7.12 (s, 2H, -Ha), 7.30-7.67 (m, 4H, -H2-5), 8.16 (d, 1H, J=8 Hz, -H1), 8.95 (d,
13
1H, J=8 Hz, -H6), 9.86 (s, 1H, -CH=N-). C-NMR (CDCl3, ppm): 56.3 (-3,5-OCH3), 61.0
(4-OCH3), 106.8, 116.0, 118.6, 121.5, 124.9, 126.8, 127.4, 131.7, 136.0, 147.4, 150.2, 153.7,
162.5, 191.0 (-CH=N-). IR (cm-1): 3094, 3063, 3010, 2942, 2835, 2754, 2718, 1683, 1587,
1505, 1457, 1422, 1381, 1327, 1270, 1231, 1186, 1124, 1037, 992, 920, 845, 820, 791, 757,
747, 730, 667, 642, 627, 595, 556, 552, 534, 520, 486, 464. Anal. Calcd. For: [C19H18N2O3]:
C: 70.79, H: 5.63, N: 8.69, Found: C: 70.86, H: 5.55, N: 8.81.
2.1.1.2. Data for N-4-methlybenzylidenequinoline-8-amine (2)
1
Color: Light Brown. Yield: 74 %. H-NMR (CDCl3, δ ppm): 2.44 (s, 3H, -4-CH3), 7.15-
7.67 (m, 6H, -H2-5, a), 7.78 (d, 1H, J=8 Hz, -H1), 8.09 (d, 2H, J=8 Hz, -Hb), 8.77 (d, 1H, J=8
4

Hz, -H6), 9.97 (s, 1H, -CH=N-). 13C-NMR (CDCl3, ppm): 29.7 (-4-CH3), 110.3, 116.0,
118.4, 121.4, 124.9, 127.6, 129.5, 129.7, 129.9, 136.4, 147.2, 149.9, 162.7, 191.9 (-CH=N-).
IR (cm-1): 3063, 3039, 3003, 2977, 2951, 2921, 2847, 1703, 1613, 1574, 1506, 1474, 1451,
1422, 1374, 1330, 1296, 1269, 1234, 1205, 1186, 1173, 1131, 1100, 1087, 1077, 1049, 1036,
1017, 994, 972, 964, 946, 894, 861, 849, 828, 814, 798, 784, 766, 754, 740, 715, 667, 639,
621, 586, 561, 539, 526, 474, 462. Anal. Calcd. For: [C17H14N2]: C: 82.90, H: 5.73, N:
11.37, Found: C: 83.02, H: 5.58, N: 11.39.
2.1.1.3. Data for N-4-nitrobenzylidenequinoline-8-amine (3)
1
Color: Yellow. Yield: 75 %. H-NMR (CDCl3, δ ppm): 6.94-7.61 (m, 4H, -H2-5), 8.08 (d,
2H, J=8 Hz, -Ha), 8.22 (d, 2H, J=8 Hz, -Hb), 8.36 (d, 1H, J=8 Hz, -H1), 9.00 (d, 1H, J=8 Hz, -
H6), 10.17 (s, 1H, -CH=N-). 13C-NMR (CDCl3, ppm): 110.0, 116.0, 118.8, 121.7, 123.9,
126.0, 126.7, 127.4, 129.9, 136.2, 147.4, 150.4, 160.4, 190.2 (-CH=N-). IR (cm-1): 3096,
3057, 3045, 3004, 2916, 2849, 1702, 1607, 1574, 1506, 1474, 1439, 1424, 1374, 1334, 1286,
1269, 1236, 1205, 1190, 1141, 1133, 1123, 1107, 1087, 1067, 1050, 1026, 1014, 987, 975,
962, 906, 867, 852, 838, 818, 812, 789, 779, 762, 751, 736, 693, 679, 667, 656, 644, 640, 630,
601, 580, 563, 538, 528, 518, 505, 494, 482, 473, 456, 449, 441, 436, 430, 419, 408. Anal.
Calcd. For: [C16H11N3O2]: C: 69.31, H: 4.00, N: 15.15, Found: C: 69.46, H: 3.92, N: 14.96.
2.1.1.4. Data for N-4-chlorobenzylidenequinoline-8-amine (4)
Color: Light Yellow. Yield: 68 %. 1H-NMR (CDCl3, δ ppm): 6.95-7.71 (m, 4H, -H2-5),7.34
(d, 2H, J=8 Hz, -Ha), 7.38 (d, 2H, J=8 Hz, -Hb), 8.08 (d, 1H, J=8 Hz, -H1), 8.78 (d, 1H, J=8
Hz, -H6), 10.00 (s, 1H, -CH=N-). 13C-NMR (CDCl3, ppm): 110.1, 116.1, 118.3, 121.3,
127.4, 128.2, 129.0, 129.5, 130.5, 136.0, 147.4, 150.2, 161.3, 190.9 (-CH=N-). IR (cm-1):
3093, 3056, 3037, 2989, 2950, 2930, 2881, 2827, 1698, 1607, 1593, 1572, 1505, 1486, 1473,
1441, 1422, 1404, 1373, 1332, 1289, 1262, 1233, 1203, 1171, 1113, 1086, 1050, 1012, 978,
906, 887, 866, 853, 815, 785, 762, 742, 711, 688, 642, 604, 588, 578, 563, 538, 529, 511, 506,
499, 488, 482, 476, 466, 446, 436, 429, 422, 415, 401. Anal. Calcd. For: [C16H11ClN2]: C:
72.05, H: 4.16, N: 10.50, Found: C: 71.89, H: 4.02, N: 10.37.
2.1.1.5. Data for N-4-dimethylaminobenzylidenequinoline-8-amine (5)
1
Color: Light Brown. Yield: 70 %. H-NMR (CDCl3, δ ppm): 3.07 (s, 6H, -4-N(CH3)2),
6.92-7.64 (m, 4H, -H2-5), 6.76 (d, 2H, J=8 Hz, -Ha), 7.35 (d, 2H, J=8 Hz, -Hb), 7.99 (d, 1H,
5

13
J=8 Hz, -H1), 8.07 (d, 1H, J=8 Hz, -H6), 9.76 (s, 1H, -CH=N-). C-NMR (CDCl3, ppm):
40.2 (-N(CH3)2), 110.0, 111.5, 116.0, 118.8, 121.4, 124.5, 127.4, 131.6, 135.9, 144.0, 147.4,
149.9, 162.3, 190.3 (-CH=N-). IR (cm-1): 3093, 3065, 3028, 2985, 2902, 2796, 2733, 2715,
2695, 1661, 1594, 1575, 1550, 1506, 1472, 1434, 1422, 1367, 1335, 1313, 1267, 1232, 1163,
1138, 1126, 1114, 1084, 1067, 1001, 974, 940, 929, 902, 856, 812, 793, 783, 756, 744, 728,
647, 634, 615, 596, 565, 544, 525, 515, 507, 489, 475, 463. Anal. Calcd. For: [C18H17N3]: C:
78.52, H: 6.22, N: 15.26, Found: C: 78.73, H: 6.12, N: 15.15.
2.1.1.6. {[N-3,4,5-trimethoxybenzylidenequinoline-8-amine]-(p-cymene)-chloro-
ruthenium(II)}chloride (6)
Color: Brown. Yield: 65 %. M.P.: 260.7 oC. 1H-NMR (DMSO-d6, δ ppm): 0.91 and 1.06
(d and d, J = 8Hz, 6 H, -Hm), 2.07 (s, 3 H, -Hk), 2.69 (m, 1H, -Hl), 3.76 (s, 3H, 4-OCH3), 3.86
(s, 6H, 3,5-OCH3), 5.80 and 5.89 (dd, 2H, J=4 Hz, -Hy), 6.08 and 6.15 (dd, 2H, J=4 Hz, -Hx),
7.78 (s, 2H, -Ha), 7.69-7.98 (m, 4H, -H2-5), 8.66 (d, 1H, J=8 Hz, -H1), 9.45 (d, 1H, J=8 Hz, -
H6), 9.71 (s, 1H, -CH=N-). 13C-NMR (DMSO-d6, ppm): 18.4 (4-CH3), 22.4 (-CH-(CH3)2),
30.5 (-CH-(CH3)2), 56.6 (-3,5-OCH3), 60.7 (4-OCH3), 82.0, 84.4, 106.4, 107.2, 121.4, 124.3,
126.8, 128.6, 129.3, 129.7, 132.1, 139.2, 140.5, 153.6, 153.8, 156. 9, 160.8, 192.4 (-CH=N-).
IR(cm-1): 3106, 3048, 3037, 2987, 2966, 2953, 2901, 2869, 2810, 1622, 1589, 1573, 1536,
1506, 1471, 1456, 1396, 1372, 1319, 1275, 1259, 1240, 1236, 1214, 1189, 1164, 1122, 1085,
1056, 916, 884, 831, 805, 793, 769, 706, 674, 636, 608, 569, 520, 503, 468, 449, 425, 402.
Anal. Calcd. For: [C29H32Cl2N2O3Ru]: C: 55.41, H: 5.13, N: 4.46, Found: C: 55.68, H: 4.89,
N: 4.39. UV–vis (λ(nm) (ε (L/(mol*cm))): 280 (39820), 383 (6980), 536 (5960).
2.1.1.7. {[N-4-methlybenzylidenequinoline-8-amine]-(p-cymene)-chloro-
ruthenium(II)}chloride (7)
o
1
Color: Brown. Yield: 62 %. M.P.: 255.2 C. H-NMR (DMSO-d6, δ ppm): 0.92 and 1.06
(d and d, J = 8Hz, 6H, -Hm), 1.23 (s, 3H, -4-CH3), 2.07 (s, 3H, -Hk), 2.67 (m, 1H, -Hl), 5.75
and 5.86 (dd, 2H, J=4 Hz, -Hy), 6.00 and 6.12 (dd, 2H, J=4 Hz, -Hx), 6.91-7.97 (m, 8H, -Ha, -
13
Hb, -H2-5), 8.66 (d, 1H, J=8 Hz, -H1), 9.05 (d, 1H, J=8 Hz, -H6), 9.69 (s, 1H, -CH=N-). C-
NMR (DMSO-d6, ppm): 18.4 (4-CH3), 21.1 (4-CH3), 22.3 (-CH-(CH3)2), 30.5 (-CH-(CH3)2),
82.8, 84.6, 100.0, 102.7, 121.9, 124.4, 126.8, 128.6, 129.4, 130.0, 130.2, 139.3, 140.4, 145.8,
147.4, 150.7, 156.9, 176.7 (-CH=N-). IR(cm-1): 3094, 3044, 2962, 2912, 2901, 2868, 2813,
6

1684, 1601, 1590, 1573, 1505, 1468, 1455, 1408, 1372, 1315, 1258, 1215, 1183, 1113 (C-C-
C, rocking), 1085, 1056, 1036, 1021, 877, 818, 788, 769, 752, 692, 674, 626, 594, 552, 538,
526, 511, 489, 483, 476, 469, 459, 445, 429, 403. Anal. Calcd. For: [C27H28Cl2N2Ru]: C:
58.69, H: 5.11, N: 5.07, Found: C: 58.55, H: 5.25, N: 5.17. UV–vis (λ(nm) (ε
(L/(mol*cm))): 286 (13780), 386 (3490), 512 (2100).
2.1.1.8. {[N-4-nitrobenzylidenequinolin-8-amine]-(p-cymene)-chloro-
ruthenium(II)}chloride (8)
o
1
Color: Brown. Yield: 70 %. M.P.: 214.9 C. H-NMR (DMSO-d6, δ ppm): 0.91 and 1.07
(d and d, J = 8Hz, 6H, -Hm), 2.07 (s, 3H, -Hk), 2.67 (m, 1H, -Hl), 5.77 and 5.88 (dd, 2H, J=4
Hz, -Hy), 6.03 and 6.14 (dd, 2H, J=4 Hz, -Hx), 6.93-7.99 (m, 8H, -Ha, -Hb, -H2-5), 8.67 (d, 1H,
J=8 Hz, -H1), 9.24 (d, 1H, J=8 Hz, -H6), 9.71 (s, 1H, -CH=N-). 13C-NMR (DMSO-d6, ppm):
18.4 (4-CH3), 22.2 (-CH-(CH3)2), 30.5 (-CH-(CH3)2), 82.0, 84.6, 100.2, 102.8, 120.6, 124.4,
126.8, 128.5, 128.7, 129.1, 130.2, 139.3, 140.5, 145.9, 150.1, 156. 9, 164.6, 190.9 (-CH=N-).
IR(cm-1): 3150, 3105, 3073, 3048, 3037, 2997, 2951, 2896, 2866, 2807, 1622, 1591, 1573,
1519, 1515, 1506, 1496, 1471, 1456, 1445, 1435, 1428, 1396, 1386, 1372, 1344, 1317, 1275,
1259, 1213, 1201, 1189, 1163, 1134, 1108, 1086, 1055, 1027, 1012, 1002, 975, 965, 916, 883,
853, 830, 804, 793, 769, 731, 697, 673, 667, 654, 636, 624, 607, 597, 569, 556, 543, 538, 518,
503, 490, 481, 475, 469, 463, 456, 447, 443, 433, 426, 415. Anal. Calcd. For:
[C26H25Cl2N3O2Ru]: C: 53.52, H: 4.32, N: 7.20, Found: C: 53.69, H: 4.18, N: 7.03. UV–vis
(λ(nm) (ε (L/(mol*cm))): 279 (35070), 380 (7480), 531 (4960).
2.1.1.9. {[N-4-chlorobenzylidenequinolin-8-amine]-(p-cymene)-chloro-
ruthenium(II)}chloride (9)
o
1
Color: Brown. Yield: 60 %. M.P.: 211.4 C. H-NMR (DMSO-d6, δ ppm): 0.91 and 1.06
(d and d, J = 8Hz, 6H, -Hm), 2.07 (s, 3H, -Hk), 2.67 (m, 1H, -Hl), 5.76 and 5.87 (dd, 2H, J=4
Hz, -Hy), 6.01 and 6.13 (dd, 2H, J=4 Hz, -Hx), 6.90-7.98 (m, 8H, -Ha, -Hb, -H2-5), 8.67 (d, 1H,
J=8 Hz, -H1), 9.21 (d, 1H, J=8 Hz, -H6), 9.70 (s, 1H, -CH=N-). 13C-NMR (DMSO-d6, ppm):
18.4 (4-CH3), 22.3 (-CH-(CH3)2), 30.5 (-CH-(CH3)2), 82.8, 84.4, 100.2, 102.8, 124.4, 126.8,
128.5, 128.7, 129.0, 129.4, 136.8, 139.3, 140.5, 145.9, 150.7, 156. 9, 161.8, 189.4 (-CH=N-).
IR(cm-1): 3105, 3074, 3049, 3038, 2954, 2901, 2869, 2812, 1622, 1591, 1573, 1508, 1489,
1470, 1445, 1397, 1387, 1373, 1319, 1260, 1214, 1190, 1164, 1135, 1088, 1056, 1028, 1013,
7

917, 883, 831, 805, 793, 770, 690, 674, 636, 624, 609, 591, 581, 569, 555, 515, 504, 490, 482,
469, 447, 426, 416. Anal. Calcd. For: [C26H25Cl3N2Ru]: C: 54.51, H: 4.40, N: 4.89, Found:
C: 54.45, H: 4.53, N: 4.92. UV–vis (λ(nm) (ε (L/(mol*cm))): 280 (27500), 386 (6570), 537
(5010).
2.1.1.10.
{[N-4-dimethylaminobenzylidenequinolin-8-amine]-(p-cymene)-chloro-
ruthenium(II)}chloride (10)
o
1
Color: Brown. Yield: 72 %. M.P.: 198.7 C. H-NMR (DMSO-d6, δ ppm): 0.92 and 1.06
(d and d, J = 8Hz, 6H, -Hm), 2.07 (s, 3H, -Hk), 2.68 (m, 1H, -Hl), 3.19 (s, 6H, -N-(CH3)2),
5.79 and 5.88 (dd, 2H, J=4 Hz, -Hy), 6.05 and 6.14 (dd, 2H, J=4 Hz, -Hx), 6.85-7.98 (m, 8H, -
Ha, -Hb, -H2-5), 8.66 (d, 1H, J=8 Hz, -H1), 9.38 (d, 1H, J=8 Hz, -H6), 9.71 (s, 1H, -CH=N-).
13C-NMR (DMSO-d6, ppm): 18.4 (4-CH3), 22.4 (-CH-(CH3)2), 30.5 (-CH-(CH3)2), 53.9 (-N-
(CH3)2), 82.1, 84.6, 100.1, 102.8, 124.3, 126.7, 128.6, 128.8, 129.0, 131.9, 136.0, 139.2,
140.5, 145.9, 148.2, 156.9, 169.1, 183.6 (-CH=N-). IR(cm-1): 3150, 3105, 3073, 3048, 3037,
2990, 2951, 2899, 2867, 2807, 1642, 1623, 1604, 1591, 1573, 1557, 1521, 1506, 1470, 1442,
1427, 1396, 1371, 1318, 1275, 1259, 1213, 1190, 1164, 1134 (C-C-C, rocking), 1116, 1086,
1055, 1026, 1001, 942, 916, 883, 830, 805, 793, 769, 729, 706, 689, 673, 636, 607, 569, 556,
543, 520, 504, 447, 431, 411. Anal. Calcd. For: [C28H31Cl2N3Ru]: C: 57.83, H: 5.37, N:
7.23, Found: C: 57.78, H: 5.41, N: 7.33. UV–vis (λ(nm) (ε (L/(mol*cm))): 280 (29080), 339
(8140), 386 (6230), 499 (6000).
2.1.2. Synthesis procedure of Sulfonamide Ligands and N-coordinate RuII complexes
N-(Quinoline-8-yl-aryl)benzenesulfonamides were synthesized by a procedure developed by
us and published in the literature [36]. A mixture of [RuCl2(p-cymene)2]2 dimer and aromatic
sulfonamide ligands was stirred and heated under argon atmosphere in dry DMF (10 ml) at 70
oC overnight. 2,2'-bipyridine-4,4'-dicarboxylic acid was added to the mixture and the
o
o
temperature increased to 130 C for 3 h. The mixture was cooled to 100 C and excess
NH4NCS was added to the reaction media and stirred for an additional 3 h. After allowing the
mixture to cool, the volatiles were removed under reduced pressure and the black residue was
stirred in H2O overnight to remove any unreacted NH4NCS. The precipitate was filtered and
solving by methanol (10 ml) and the solvent was concentrated to 3 ml under vacuum. Diethyl
ether (5 ml) was added to the concentrate solution and the pure product was collected by
filtration (Figure-2).
INSERT FIGURE-2
8

2.1.2.1. {[N,N’O-Quinoline-8-yl-4-n-propyl-benzenesulfonamidate]-[N,N’-2,2’-bipyridine-
4,4’- di-carboxylic acid]-thiocyanate-ruthenium(II)]} (16)
Color: Black. Yield: 48 %. M.P.: 109.3 oC. 1H-NMR (DMSO-d6, δ ppm): 0.81 (t, J = 8 Hz,
3H, -CH2CH2CH3), 1.19 (t, J = 8 Hz, 2 H, -CH2CH2CH3), 1.51 (m, 2H, -CH2CH2CH3), 5.73
ı
ı
(d, J = 8 Hz, 2H, -Hy ), 5.96 (s, 2H, -Hzı), 6.27 (d, J = 8 Hz, 2H, -Hx ), 7.11-7-69 (m, 6H, -H1-
6), 7.17 (d, J = 8 Hz, 2H, -Hb), 7.77 (d, J = 8 Hz, 2H, -Ha), 7.95 (s, 2H, -Hz), 8.43 (d, J = 8 Hz,
13
2H, -Hy), 8.64 (br. 2H, -OH), 9.48 (d, J = 8 Hz, 2H, -Hx). C-NMR (DMSO-d6, ppm): 14.0
(-CH2CH2CH3), 34.6 (-CH2CH2CH3), 45.9 (-CH2CH2CH3), 116.9, 117.3, 122.2, 122.5, 123.4,
125.9, 127.9, 128.3, 128.5, 128.7, 128.8, 129.9, 135.3, 139.0, 144.3, 146.4, 154.3, 162.8,
170.9 (-COOH). IR(cm-1): 3428, 3105, 3081, 3059, 2962, 2933, 2870, 2798, 2105, 2045,
2004, 1982, 1951, 1705, 1653, 1596, 1571, 1545, 1505, 1464, 1403, 1377, 1316, 1292, 1272,
1260, 1229, 1191, 1147, 1134, 1110, 1083, 1041, 1013, 969, 948, 908, 869, 841, 830, 807,
788, 758, 747, 720, 701, 677, 667, 650, 635, 610, 585, 563, 542, 526, 516, 504, 497, 484, 468,
458. Anal. Calcd. For: [C31H25N5O6RuS2]: C: 51.09, H: 3.46, N: 9.61, Found: C: 51.22, H:
3.57, N: 9.53. UV–vis (λ(nm) (ε (L/(mol*cm))): 262 (16426), 310 (7219), 406 (3453), 535
(1315).
2.1.2.2. {[N,N’O-Quinoline-8-yl-4-t-buthyl-benzenesulfonamidate]-[N,N’-2,2’-bipyridine-
4,4’- di-carboxylic acid]-thiocyanate-ruthenium(II)]} (17)
o
1
Color: Black. Yield: 55 %. M.P.: 129.8 C. H-NMR (DMSO-d6, δ ppm): 1.26 (s, 9H, -
ı
ı
C(CH3)3), 5.73 (d, J = 8 Hz, 2H, -Hy ), 5.96 (s, 2H, -Hzı), 6.27 (d, J = 8 Hz, 2H, -Hx ), 7.23-
7.81 (m, 6H, -H1-6), 7.32 (d, J = 8 Hz, 2H, -Hb), 7.51 (d, J = 8 Hz, 2H, -Ha), 8.00 (s, 2H, -Hz),
8.44 (d, J = 8 Hz, 2H, -Hy), 8.71 (br. 2H, -OH), 9.48 (d, J = 8 Hz, 2H, -Hx). 13C-NMR
(DMSO-d6, ppm): 31.5 (-C(CH3)3), 34.6 (-C(CH3)3), 117.0, 117.3, 123.4, 124.8, 125.7,
128.1, 128.8, 129.7, 130.0, 135.4, 138.9, 144.3, 145.9, 149.5, 151.4, 154.3, 154.5, 158.8,
177.3 (-COOH). IR(cm-1): 3435, 3055, 2963, 2902, 2870, 2775, 2105, 2045, 1959, 1704,
1596, 1572, 1544, 1501, 1463, 1396, 1376, 1316, 1302, 1261, 1231, 1189, 1142, 1109, 1009,
1081, 1044, 1020, 1008, 970, 947, 903, 874, 836, 820, 803, 792, 776, 759, 748, 722, 702, 684,
664, 624, 580, 562, 550, 523, 485, 470. Anal. Calcd. For: [C32H27N5O6RuS2]: C: 51.74, H:
3.66, N: 9.43, Found: C: 51.96, H: 3.71, N: 9.35. UV–vis (λ(nm) (ε (L/(mol*cm))): 261
(11506), 309 (6666), 397 (2504), 535 (1210).
9

2.1.2.3. {[N,N’O-Quinoline-8-yl-4-chloro-benzenesulfonamidate]-[N,N’-2,2’-bipyridine-
4,4’- di-carboxylic acid]-thiocyanate-ruthenium(II)]} (18)
o
1
Color: Black. Yield: 50 %. M.P.: 101.2 C. H-NMR (DMSO-d6, δ ppm): 5.77 (d, J = 8
ı
Hz, 2H, -Hy ), 5.97 (s, 2H, -Hzı), 6.28 (d, J = 8 Hz, 2H, -Hxı), 7.08-7.88 (m, 6H, -H1-6), 7.37 (d,
J = 8 Hz, 2H, -Hb), 7.59 (d, J = 8 Hz, 2H, -Ha), 7.95 (s, 2H, -Hz), 8.35 (d, J = 8 Hz, 2H, -Hy),
13
8.72 (br. 2H, -OH), 9.41 (d, J = 8 Hz, 2H, -Hx). C-NMR (DMSO-d6, ppm): 117.4, 122.3,
122.7, 126.6, 127.9, 128.2, 128.3, 128.8, 129.0, 130.0, 133.5, 137.6, 139.1, 147.6, 150.8,
162.8, 166.5, 169.3. IR(cm-1): 3426, 3059, 2978, 2925, 2799, 2107, 2043, 2001, 1956, 1705,
1653, 1604, 1575, 1544, 1501, 1464, 1403, 1374, 1314, 1297, 1259, 1227, 1182, 1146, 1129,
1112, 1100, 1086, 1037, 1010, 969, 948, 909, 875, 839, 828, 801, 784, 773, 757, 748, 721,
705, 683, 664, 649, 615, 601, 565, 555, 526, 505, 484, 479, 470, 464, 456. Anal. Calcd. For:
[C28H18ClN5O6RuS2]: C: 46.64, H: 2.52, N: 9.71, Found: C: 46.59, H: 2.47, N: 9.75. UV–vis
(λ(nm) (ε (L/(mol*cm))): 260 (7765), 311 (5126), 389 (1752), 524 (1269)
2.1.2.4. {[N,N’O-Quinoline-8-yl-4-methoxy-benzenesulfonamidate]-[N,N’-2,2’-bipyridine-
4,4’- di-carboxylic acid]-thiocyanate-ruthenium(II)]} (19)
o
Color: Black. Yield: 58 %. M.P.: 98.2 C. 1H-NMR (DMSO-d6, δ ppm): 3.74 (s, 3H, -
ı
ı
OCH3), 5.73 (d, J = 8 Hz, 2H, -Hy ), 5.97 (s, 2H, -Hzı), 6.27 (d, J = 8 Hz, 2H, -Hx ), 6.56-7.77
(m, 6H, -H1-6), 6.86 (d, J = 8 Hz, 2H, -Hb), 7.54 (d, J = 8 Hz, 2H, -Ha), 7.95 (s, 2H, -Hz), 8.28
(d, J = 8 Hz, 2H, -Hy), 8.75 (br. 2H, -OH), 9.37 (d, J = 8 Hz, 2H, -Hx). 13C-NMR (DMSO-d6,
ppm): 55.6 (-OCH3), 113.2, 113.9, 117.9, 123.2, 126.8, 127.5, 129.1, 130.0, 130.7, 132.5,
134.2, 137.9, 141.3, 145.6, 148.0, 159.7, 162.8, 166.2, 170.9 (-COOH). IR(cm-1): 3410, 3063,
2966, 2902, 2799, 2771, 2109, 2045, 1951, 1706, 1660, 1594, 1547, 1497, 1461, 1440, 1404,
1373, 1309, 1252, 1230, 1186, 1131, 1111, 1085, 1041, 1019, 969, 949, 901, 861, 824, 804,
769, 747, 720, 697, 682, 663, 573, 558, 542, 527, 517, 498, 484, 469, 459. Anal. Calcd. For:
[C29H21N5O7RuS2]: C: 48.60, H: 2.95, N: 9.77, Found: C: 48.71, H: 3.02, N: 9.69. UV–vis
(λ(nm) (ε (L/(mol*cm))): 260 (12461), 312 (9560), 416 (2761), 525 (1786).
2.1.2.5. {[N,N’O-Quinoline-8-yl-benzenesulfonamidate]-[N,N’-2,2’-bipyridine-4,4’- di-
carboxylic acid]-thiocyanate-ruthenium(II)]} (20)
o
1
Color: Black. Yield: 50 %. M.P.: 121.9 C. H-NMR (DMSO-d6, δ ppm): 5.75 (d, J = 8
ı
ı
Hz, 2H, -Hy ), 5.97 (s, 2H, -Hzı), 6.28 (d, J = 8 Hz, 2H, -Hx ), 7.14-7.70 (m, 7H, -H1-6,c), 7.90
(t, J = 8 Hz, 2H, -Hb), 7.94 (s, 2H, -Hz), 8.44 (d, J = 8 Hz, 2H, -Hy), 8.77 (br. 2H, -OH), 8.90
10

(d, J = 8 Hz, 2H, -Ha), 9.49 (d, J = 8 Hz, 2H, -Hx). 13C-NMR (DMSO-d6, ppm): 117.1,
117.4, 120.0, 123.5, 123.9, 125.9, 128.1, 128.7, 128.9, 129.7, 130.0, 131.9, 139.0, 140.3,
151.1, 156.0, 162.8, 166.5. IR(cm-1): 3390, 3111, 3046, 2988, 2972, 2921, 2902, 2777, 2101,
2027, 1955, 1709, 1653, 1604, 1567, 1545, 1504, 1460, 1445, 1405, 1375, 1365, 1315, 1299,
1258, 1229, 1190, 1142, 1112, 1085, 1068, 1037, 1013, 947, 914, 903, 876, 864, 816, 758,
715, 682, 664, 615, 579, 566, 524, 493, 477, 460. Anal. Calcd. For: [C28H19N5O6RuS2]: C:
48.97, H: 2.79, N: 10.20, Found: C: 49.06, H: 2.65, N: 10.18. UV–vis (λ(nm) (ε
(L/(mol*cm))): 259 (16328), 309 (11888), 397 (4508), 497 (3636).
2.1.3. DSSC Fabrication and Photovoltaic Measurements
Herein, the test cell titania electrodes (FTO coated glass, screen-printing technology Ti-
nanoxide, Active layer from Ti-Nanoxide T/SP covered by a reflective layer of Ti-Nanoxide
R/SP, 6 x 6 mm active area), platinum electrodes (FTO coated glass, screen-printing
technology, drilled for electrolyte filling), gaskets, sealing caps and masks were produced by
Solaronix SA, Switzerland.
The selected the TiO2 photoanode were dipped into the sensitizer solutions (0.3 mM, DMSO)
to complete adsorption at ambient temperature for 24 h. The dye-loaded TiO2 film
as
working electrode and Pt-coated FTO as CE were separated by a sealing material (Meltonix
1170-60) and sealed together by pressing them under heat. The iodolyte liquid electrolyte
(Solaronix, Iodolyte AN 50) was introduced via two holes made previously on the CE and the
holes were sealed with Meltonix 1170-60 and a glass cover slip. The PCEs of working
devices was occurred by recording the current density – voltage (J-V) curves with a Metrohm
Autolab PGSTAT101 device under illumination of a simulated AM 1.5 solar light. A black
mask with an aperture area of 0.36 cm2 was used during measurement to avoid stray light.
11

3. RESULT AND DISCUSSION
3.1. Characterization data
The synthetic route of N-donor ligands and their RuII complexes (6-10, 16-20) are shown in
Figures-1,2. The commercially available starting materials 8-aminoquinoline, aromatic
aldehydes, aromatic sulfonylchloride, [RuCl2(p-cymene)]2 and 2,2'-bipyridine-4,4'-
dicarboxylic acid were subjected to the general procedure followed by their desired
conversion products from Schiff base to sulfonamide ligands.
In the 1H-NMR spectra of the Schiff base ligands 1-5, the –Ha protons were located between
7.12 ppm as a singlet for 1 and 7.34-8.08 ppm as a doublet for 2-5. Similarly, the –Hb protons
were assigned around 7.38 – 8.22 ppm as a doublet peak for 2-5. The protons for the 3,5-
OCH3 and 4-OCH3 groups for 1, the -4-N(CH3)2 group for 5 could be located at 3.92 ppm,
1
3.94 ppm and 3.07 ppm as singlet peaks, respectively. Schiff base ligands 1-5 exhibit H-
NMR chemical shifts at δ= 9.86, 9.97, 10.17, 10.00 and 9.76 ppm, respectively, for the
characteristic -CH=N- proton atom. For the 6-10 RuII complexes, similarly to the ligands, the
aromatic –CH- protons were assigned between 6.85 – 9.45 ppm. The protons for the 3,5-
OCH3 and 4-OCH3 groups for 6 and the -4-N(CH3)2 group for 10 were observed at 3.86 ppm,
3.76 ppm and 3.19 ppm as singlet peaks, respectively. Also, the chemical shift values of the
imine bond protons for 6-10 were found around 9.69 – 9.71 ppm. Additionally, the -Hm, -Hk, -
Hl, -Hy and -Hx protons for over the p-cymene group were observed at around 0.91-1.07 ppm,
2.07 ppm, 2.67-2.69 ppm, 5.76-5.89 ppm and 6.01-6.14 ppm, respectively. The complexes 6-
10 exhibit 13C-NMR chemical shifts at δ= 192.4, 176.7, 190.9, 189.4 and 183.6 ppm,
respectively, for the characteristic -CH=N- carbon atom, and the values are comparable to
those of other reported imine bond complexes [37]. Also, the imine bond frequency was
shown as expected at around 1622-1684 cm-1 in the IR spectrum.
1
In the H-NMR spectra of the N-coordinate RuII complexes (16-20), -H1-6 for over the
quinoline ring and -Ha-c relating to the sulfonamidate ring were assigned between 6.56 – 7.88
ppm and 6.86 – 8.90 ppm, respectively. The peaks of aromatic protons -Hx or -Hxı, -Hy or -Hyı
and -Hz or -Hzı relating to the bidentate N-donor ligand (2,2'-bipyridine-4,4'-dicarboxylic
acid) were located at around δ= 8.90 – 9.48 or 6.27 – 6.28 ppm as a doublet, 8.28 – 8.44 or
5.73 – 5.75 ppm as a doublet, 7.94 – 8.00 or 5.96 – 5.97 ppm as a singlet, respectively.
12

In (c) position, -CH2CH2CH3 protons and carbons were assigned at δ 1.19 ppm as a triplet and
45.9 ppm, at δ 1.51 ppm as a multiplet and 34.6 ppm, at δ 0.81 ppm as a triplet and 14.0 ppm
for 16; -C(CH3) protons and carbons were exhibited at δ 1.26 ppm as singlet with the integral
height corresponding to nine proton and carbon peaks at δ 34.6, 31.5 ppm for 17, respectively;
and a singlet peak belonging to -OCH3 protons / carbon was also observed at δ 3.74 ppm with
a three unit integral height and at δ 55.6 ppm for 19. The NMR chemical shifts and
integrations of signals were consistent with the proposed structure. In addition, for the
infrared spectroscopy (IR) results of the complexes 16-20, the N─H stretching frequency
peaks over sulfonamide groups in the corresponding ligands disappeared on the spectrum and
the frequency peaks of the –COOH group belonging to the 2,2'-bipyridine-4,4'-dicarboxylic
acid ligand was located at ≈ 3400 cm-1 for 16-20.
3.1.
Optical and Electronic Properties
The UV-Vis absorption spectra of N-coordinate RuII complexes (6-10 (a) and 16-20 (b)) in
DMSO solution (1x10-5 M and 1x10-4 M) are shown in Figures-S-1,2. and related optical data
are summarized in Table-1. The data showed that for all the complexes, the metal ligand
charge-transfer peaks (MLCT) [Ru(dπ)→π*], π→π* and n→π* peaks were shown that at
between 386 – 536 nm, 309 – 386 nm and 259 – 280 nm, respectively. In all cases, the
transitions in the visible region were located as MLCT while the band at lower wavelengths
and the ligand centered electronic transitions exhibited at < 400 nm. Overall, the complexes
bearing a sulfonamide fragment, thiocyanate and 2,2'-bipyridine-4,4'-dicarboxylic acid
ligands (16-20) show the most promising optical properties in terms of bandgap energy (Eg)
while the RuII complexes containing an imine bond and p-cymene group (6-10) showed a
wider bandgap. We compared to the optical properties of all the complexes (6-10, 16-20) with
Z907 dye as reference. Concerning the absorption band in the visible range, a blue shift in the
λmax for all the dyes with respect to Z907 (λ(nm) (ε (L/(mol*cm))): 298 (29790), 320 (29890),
428 (11290), 546 (11430) in Figure-S-2f (1x10-5 M in DMSO) was founded whereas the
molar extinction coefficients for the sensitizers (6-10, 16-20) are moderate compared to Z907.
13

INSERT TABLE-1
The HOMO and LUMO levels of the molecules are requisite data to identify the facilitate of
electron injection from the excited sensitizer to the conduction band (Ecb) of titanium dioxide
(TiO2) and the subsequent dye regeneration. ODPV was achieved with 0.1 M
tetrabutylammonium perchlorate (TBAP) as supporting electrolyte in DMSO solution
(Figures-S-3,4). All potentials were internally referenced to the ferrocene/ferrocenium
(Fc/Fc+) couple which has the redox potential of (EFc/Fc+) 0.510V versus Ag/AgCl. The first
oxidation potentials of the sensitizers (6-10, 16-20) were detected as peak potentials from the
ODPV curves and associated in the Table-1. The Eoxd of the RuIII/II are 0.66, 0.70, 0.63, 0.61,
0.62 V for 6-10 and 0.53, 0.55, 0.58, 0.59, 0.58 V for 16-20, respectively (Figures-S-3,4 and
-
Table-1). The HOMO for 6-10 and 16-20 are sufficiently more negative than I-/I3 electrolyte
and provide sufficient driving force for influential dye regeneration. The LUMO levels of all
the sensitizers were calculated by ELUMO = EHOMO + Eg formula [38, 39] and are -3.49, -3.55, -
3.47, -3.47, -3.47 eV for 6-10 and -3.43, -3.44, -3.52, -3.49, -3.51 eV for 16-20, respectively,
and are more positive than those of the conduction band edge of TiO2 (-4.26 eV) providing an
productive electron injection process from the excited state of the sensitizers into the TiO2
photoanode layer. The schematic energy levels of N-coordinate RuII complexes (6-10 (a), 16-
20 (b)) are shown in Figure-3.
INSERT FIGURE-3
3.2.
Photovoltaic Performances For DSSC
The explanations of the solar cells fabrication is showed in the DSSC fabrication and
photovoltaic measurements section. Then from the optical and electrochemical data, various
DSSCs were produced with the aim of testing the photovoltaic properties of ruthenium(II)
complexes such as 6-10 and 16-20. The current (J) – voltage (V) curves are recorded as the
average of three measurements in Fig-4, Fig-S5 and the corresponding photovoltaic data of
the working devices are shown that in Table-2.
14

We used as a starting point standard conditions to, the test of RuII complexes bearing an imine
bond (6-10) see but we could not get positive results in terms of power conversion efficiency
(PCE, ƞ) Table-2 entries 1-5. Namely, we found that devices containing 6-10 as a sensitizer
have reduced open-circuit voltage (Voc) and short-circuit current (Jsc) in comparison to Z907
and hence an overall lower PCE. For the 6-10 sensitizers, the Jsc and Voc data were found to
be between 0.25 – 0.56 mA/cm2 and 259 – 358 mV and the PCE (ƞ %) results were measured
as 0.05%, 0.03%, 0.07%, 0.1% and 0.05%, respectively in Figure-S5. According to the data in
Table-2 entries 1-5, the lowered Jsc and Voc values were observed for cells containing 6-10,
Due to this, we encountered lower PCE and lower fill factor (FF). Then, we selected the {[N-
quinoline-8-yl-benzenesulfonamido]-(p-cymene)-chloro-ruthenium(II)} (SD-E1311) complex
reported in our previous papers [36] with the thought of achieving a different result and tested
it as the sensitizer, see Table-2. Furthermore, we tried to improve the photovoltaic
performance of the DSSC devices with the addition of 2,2'-bipyridine-4,4'-dicarboxylic acid
ligand, [SCN]- and a new backbone structure (the benzenesulfonamidate) because of their
(the complexes bearing an imine bond) easy hydrolysis and lowered catalytic efficiency in a
similar photochemical reaction compared to other N-coordinate complexes [36-43] in the
molecular structure of ligands. When we examined the fabricated new DSSC devices with the
synthesized RuII complexes (16-20) in light of this understanding, a serious increase in the Jsc
and Voc values and hence the final efficiency was shown the Jsc and Voc values were found at
between 4.19 – 5.15 mA/cm2 and 441 – 532 mV and the performance rates of the DSSCs
were found as 1.26 (ƞ%), 1.08 (ƞ%), 1.58 (ƞ%), 0.9 (ƞ%) and 1.36 (ƞ%), respectively, as seen
in Figure-4. The best performance has obtained with {[N,N’O-Quinoline-8-yl-4-chloro-
benzenesulfonamidate]-[N,N’-2,2’-bipyridine-4,4’-di-carboxylic
acid]-thiocyanate-
ruthenium(II)]} (18) with a max. PCE of 1.58%, due to the highest short-circuit current and
open-circuit voltage.
INSERT TABLE-2
Generally, the photocurrent density (Jsc) has more than very limited the performances of
devices employing 6-10 sensitizers, see Table-2. The corresponding low photocurrent
densities are likely to be the result because of electron injection problems caused by an
inadequate localization of the electron density in the excited state. The photovoltaic data of
15

the sensitizers (16-20) produced to overcome this negative condition are very convenient due
to the positions of the new functional groups and ligands. Namely, the regeneration process of
ruthenium dyes proceed via the formation of an intermediate species between the RuII
oxidized sensitizer and iodide ions in the electrolyte [44]. Furthermore, the generally accepted
mechanism for the interaction between the oxidized sensitizer and iodide is the binding of
iodide to the S atom of the [SCN]- ligand [45] as approved by theoretical calculations [46]. In
light of this information, N-coordinate ruthenium(II) complexes (16-20) bearing
sulfonamidate fragment, the two carboxylic anchoring groups suggest a strong adsorption
onto the titania surface and the [SCN]- provides the appropriate energy level, provided higher
photovoltaic data than the 6-10 complexes containing an imine bond and p-cymene ligand.
Thus, owing to these molecular changes were performed ten times for performance
improvement.
INSERT FIGURE-4
4. CONCLUSION
To summarize herein, we reported the design and synthesis of two new series of RuII
complexes (6-10 bearing an imine bond plus p-cymene ligand and 16-20 bearing a
sulfonamidate fragment plus 2,2'-bipyridine-4,4'-dicarboxylic acid as the anchor group) based
on an 8-aminoquinoline backbone. The sensitizers were characterized by NMR, IR, elemental
analysis, and optoelectronic properties recording and by the UV-vis absorption spectra and
cyclic voltammetry in solution media.
All the complexes exhibit good optical and electronic properties with an enough positioning
of energy levels notedly for 16-20 complexes. The basic state Eoxd data are more positive in
proportion to those of the I-/I-3 redox couple which should be an adequate driving force for the
productive photoactive sensitizer regeneration process, and the excited state E* data are
oxd
more negative compared to those of the Ecb edge of TiO2 providing an effective e- injection
mechanism.
After the optoelectronic approach studies, all the RuII complexes (6-10, 16-20 and SD-E1311)
were tested as photoactive dyes in solar cell devices with iodine based electrolyte and the
platinum counter electrode. Although the performance improvement process was successful
16

for our sensitizers, the overall PCE were remained low compared to the reference Z907 dye.
However, the effect of molecular variations on device performance was clearly observed and
the presence of our sensitizers bearing electron-withdrawing on DSSC has a beneficial effect
in terms of PCE. Thus the best sensitizer was found as {[N,N’O-Quinoline-8-yl-4-chloro-
benzenesulfonamidate]-[N,N’-2,2’-bipyridine-4,4’-di-carboxylicacid]-thiocyanate-
ruthenium(II)]} (18) with a maximum PCE of 1.58%. Further developments may be
obtainable by the modification and redesign of molecular structures.
Acknowledgements
The financial support granted by Erciyes University (ERUBAP) (FDK-2015-6013, ID: 6013)
is acknowledged. We would like to thank Nilgün Kayacı and Yeşim Yıldız for their help.
REFERENCES
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20

Table-1 Electrochemical and Optical data of ruthenium sensitizers
Sensitizers
Eoxd [V]b Eg [eV]c EHOMO [eV]d ELUMO [eV]e
λmax [nm]a
536
6
7
8
9
10
16
17
18
19
20
0.66
0.70
0.63
0.61
0.62
0.53
0.55
0.58
0.59
0.58
1.97
1.95
1.96
1.94
1.95
1.90
1.91
1.86
1.90
1.87
-5.46
-5.50
-5.43
-5.41
-5.42
-5.33
-5.35
-5.38
-5.39
-5.38
-3.49
-3.55
-3.47
-3.47
-3.47
-3.43
-3.44
-3.52
-3.49
-3.51
512
531
537
499
535
535
524
525
497
a UV-vis spectrums were performed in DMSO.
b Oxidation potentials (Eoxd) were recorded by oxidative differential pulse voltammetry
(ODPV).
c The bandgap energy (Eg), estimated via the onset of the absorbtion spectra in DMSO
Eg=1241/λonset.
d EHOMO = –Eox + (–4.8)
e ELUMO = EHOMO + Eg
Table-2 Photovoltaic data of working devices employing ruthenium(II) sensitizers
Entry
RuII
Jsca (mA/cm2)
0.49
Vocb (mV)
261
FFc
0.37
0.44
0.44
0.49
0.40
0.56
0.54
0.59
0.50
0.59
0.70
0.51
ƞd (%)
0.05
0.03
0.07
0.10
0.05
1.26
1.08
1.58
0.90
1.36
6.30
0.12
1
2
6
7
0.25
0.53
0.56
0.33
4.53
4.19
5.15
4.08
259
295
358
337
496
479
518
441
3
8
4
9
10
5
6
16
17
7
8
18
19
9
4.32
13.0
0.47
532
691
508
10
11
12
20
Z907
SD-E1311
a Short-circuit current density
b Open-circuit voltage
c Fill Factor
d Power conversion efficiency
21

Figure-1 Synthesis scheme of Schiff base ligands and their RuII complexes
22

Figure-2 Synthesis scheme of sulfonamide ligands and N-coordinate RuII complexes (16-20)
23

Figure-3 The schematic energy levels of N-coordinate RuII complexes (6-10 (a), 16-20 (b))
based on absorption and electrochemical data.
24

6.0
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
(16)
(17)
(18)
(19)
(20)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Voltage (V)
Figure-4 Current (J) – Voltage (V) curves of N-coordinate RuII complexes bearing
sulfonamide group (16-20).
25

► We have reported the design and synthesis of two new series of RuII complexes.
► The design steps of the complexes are shaped according to the properties of the sensitizer.
► The designed-RuII complexes are founded average photoactive sensitizers.
► The best sensitizer was found as (18) with a maximum PCE of 1.58%.
26

27