**1. Introduction**

The current environmental problems and the energy crisis have led to creating new technologies. The renewable energies such as: biofuels, biomass, wind, geothermal, hydraulic, solar, tidal, among others become the main source of the energy generation. The use of solar cells represents an alternative among renewable energies. The development of new materials goes from inorganic structures until polymers, small molecules as organic photovoltaic (OPV) and photosensitized organic materials [1].

In this context, the discovery of ultrafast charge transfer between the semiconductor polymer and inorganic semiconductors have allowed that the OPV have

passed in a decade of values close to 1% of efficiency until exceeding 10% [2]. This rapid evolution is motivated by its high potential for generating flexible, lightweight and low cost panels changing the classic concept of panels photovoltaic. In the case of the traditional polymers, the electrons are highly localized and require great energy to be excited (>5 eV) converting them into electrical insulators. In contrast, in conjugated polymer and structures the electrons from Z orbitals form π-type bonds that are associated with lower energies, corresponding to the range of ultraviolet and visible radiation. In molecular solids the transition π ! π\* that occurs between the occupied molecular orbital of higher energy (HOMO) and the lower energy of orbital (LUMO) determine the equivalent to the forbidden band energy of inorganic semiconductors [3, 4]. On the other hand, they had developed sensitized cell from organic dyes. These are also called Grätzel cells. Photoelectrons that introduce into the conduction band of TiO2 that works as a semiconductor, under light illumination [5].

anchoring groups are necessary for electron injection [14, 15] thus various functional groups can be installed to block the electrolyte from interacting with the surface or absorb more light. Then, the performance of these successful sensitizers encompasses ligands that combine extended π-conjugated systems, aspiring to enhance the optical absorptivity of the semiconductor's surface, along with long hydrophobic alkyl chains, aiming an increase of tolerance against water attack (**Table 1**). Equally importantly **N719**, which essentially differ only in the protonation state of tetra-protonated parent dye **N3**, afford a nearly quantitative conversion of incident photons into electric current over a large spectral range. The improved efficiency of **N719**, was mainly attributed to the increased cell voltage. Since 1993, chemical modifications of these early Ru(II) complexes have led to researchers achieving power conversion efficiencies up to 11.7% (**C106** dye) [16–24], where one of the DCBPy ligands has been replaced with an extended conjugation using thiophenes and long alkyl chains, lastly, these prevents interfacial

*Ligands and Coordination Compounds Used as New Photosensitized Materials…*

*DOI: http://dx.doi.org/10.5772/intechopen.92268*

The so-called solar cells sensitized by a dye are a type of hybrid devices that have reached a higher degree of development so far. Within his field, porphyrins represent a very interesting alternative because there is efficient model harnessing sunlight. These systems can be synthetized in bulk heterojunction (BHJ) organic solar cells. The interaction of macrocycles with metal ions such as: Fe2+, Fe3+, Co2+, Co3+, Ni2+, Zn2+, Cu2+, Ru2+, Pd2+ and Pt2+ and hydrogen, alkyl, cycloalkyl, cyclohexyl, cycloheptyl, cyclooctyl, haloalkyl, perhaloalkyl, ether chains have permitted the stabilizations of promising new collections. In dye-sensitized solar porphyrin-based

photosensitizers have demonstrated their potential as large and rigid planar conjugated structures, which enhance p-electron delocalization and promote intermolecular π-π interaction, as well charge transport in devices. A problem that they can presents is the effect by lack of light-harvesting beyond 850 nm, thus limiting their cell performance. In the papers, it has been reported that 50% of the total solar phonon flux is located in the red and near-infrared spectra. Zhu and colleagues had reported in 2016 that is quite urgent to develop efficient NIR absorbing molecules for high performance organic solar cells. In the next table, the authors show different publications about the development of new bioinspired

The DSSC free organic dyes are sensitized molecules whose perspective are aimed at staking, on top of one other in order to obtain panchromatic absorption. **Table 3** shows azo, cyano, thiophene, and carbonyl with highly conjugated. A PCE value at 14.7 has been reported by Kakiag et al. [49]. The PCE increase with Voc and Jsc and the best properties were associated with carboxylic group and highly polar-

The extension of the conjugated chain and the substitution of the thiophene groups do not represent a marked difference that allows concluding a relationship

Therefore, this article reports the bibliographic revision for these compounds, specifying the following parameters: Chemical name, abbreviation, structure, power conversion efficiencies (PCE), Jsc (short-circuit-current), Voc (open circuit

recombination [25].

**1.2 Porphyrins**

push-pull.

porphyrin materials (**Table 2**).

izability in the presence of nitrile group.

voltage) electrolyte used and authors.

**121**

between the photovoltaic properties and the structure.

**1.3 Metal-free organic dyes**

Dye-sensitized cell (DSSC) have been developed as functional biomimetic models of biological process. In the nature exists dyes with electronic properties that allows to purpose design news in solar panel. Chlorophyll, constituted an example in where there is light absorption and charge-carrier transport. The organic molecule is coupled to semiconductor enhancing the Gap band. This electronic transfer promote absorption to the visible region, which increase its applications [6].

The researchers in a world context have designed, developed and synthetized ruthenium complexes, porphyrins, metal-free organic dyes and organic molecules in this field.

## **1.1 Ruthenium complexes**

The efficiency of DSSC depends on different requirements listed below [7, 8]:


Different types of dyes have been tested in the DSSC setting, including: transition-metal complexes, organic dyes, porphyrins and phthalocyanines [9–12]; however, in terms of photovoltaic performance and long-term stability, Ru(II) complexes comprise the most successful family of DSSCs sensitizers, shown in **Table 1**. A study on these champion dyes reveals that majority are derivate of **N3**. The **N3** dye represents the first high-performance Ru(II) sensitizer reported in 1993 by Grätzel and co-workers [13], affording power conversion efficiencies of 10.3%. The chemical modification of **N3** and **N719** is made possible because only two

*Ligands and Coordination Compounds Used as New Photosensitized Materials… DOI: http://dx.doi.org/10.5772/intechopen.92268*

anchoring groups are necessary for electron injection [14, 15] thus various functional groups can be installed to block the electrolyte from interacting with the surface or absorb more light. Then, the performance of these successful sensitizers encompasses ligands that combine extended π-conjugated systems, aspiring to enhance the optical absorptivity of the semiconductor's surface, along with long hydrophobic alkyl chains, aiming an increase of tolerance against water attack (**Table 1**). Equally importantly **N719**, which essentially differ only in the protonation state of tetra-protonated parent dye **N3**, afford a nearly quantitative conversion of incident photons into electric current over a large spectral range. The improved efficiency of **N719**, was mainly attributed to the increased cell voltage. Since 1993, chemical modifications of these early Ru(II) complexes have led to researchers achieving power conversion efficiencies up to 11.7% (**C106** dye) [16–24], where one of the DCBPy ligands has been replaced with an extended conjugation using thiophenes and long alkyl chains, lastly, these prevents interfacial recombination [25].

#### **1.2 Porphyrins**

passed in a decade of values close to 1% of efficiency until exceeding 10% [2]. This rapid evolution is motivated by its high potential for generating flexible, lightweight and low cost panels changing the classic concept of panels photovoltaic. In the case of the traditional polymers, the electrons are highly localized and require great energy to be excited (>5 eV) converting them into electrical insulators. In contrast, in conjugated polymer and structures the electrons from Z orbitals form π-type bonds that are associated with lower energies, corresponding to the range of ultraviolet and visible radiation. In molecular solids the transition π ! π\* that occurs between the occupied molecular orbital of higher energy (HOMO) and the lower energy of orbital (LUMO) determine the equivalent to the forbidden band energy of inorganic semiconductors [3, 4]. On the other hand, they had developed sensitized cell from organic dyes. These are also called Grätzel cells. Photoelectrons that introduce into the conduction band of TiO2 that works as a semiconductor, under

*Stability and Applications of Coordination Compounds*

Dye-sensitized cell (DSSC) have been developed as functional biomimetic models of biological process. In the nature exists dyes with electronic properties that allows to purpose design news in solar panel. Chlorophyll, constituted an example in where there is light absorption and charge-carrier transport. The organic molecule is coupled to semiconductor enhancing the Gap band. This electronic transfer pro-

The researchers in a world context have designed, developed and synthetized ruthenium complexes, porphyrins, metal-free organic dyes and organic molecules

The efficiency of DSSC depends on different requirements listed below [7, 8]:

i. Broad and strong absorption, preferably extending from energies greater

ii. The dye needs to be photochemically, thermally, and electrochemically robust within the DSSC in order to withstand the harsh conditions of a

iii. Firm, irreversible adsorption to the semiconductor's surface (TiO2) and strong electronic coupling between its excited state and the semiconductor

iv. Reduction potential is sufficiently higher than the semiconductor conduction band Edge in order to enable charge injection.

Different types of dyes have been tested in the DSSC setting, including: transition-metal complexes, organic dyes, porphyrins and phthalocyanines [9–12]; however, in terms of photovoltaic performance and long-term stability, Ru(II) complexes comprise the most successful family of DSSCs sensitizers, shown in **Table 1**. A study on these champion dyes reveals that majority are derivate of **N3**. The **N3** dye represents the first high-performance Ru(II) sensitizer reported in 1993 by Grätzel and co-workers [13], affording power conversion efficiencies of 10.3%. The chemical modification of **N3** and **N719** is made possible because only two

regeneration and charge-injection processes.

v. Chemical stability in the ground and the excited states for rapid dye

mote absorption to the visible region, which increase its applications [6].

light illumination [5].

in this field.

**120**

**1.1 Ruthenium complexes**

than 900 nm.

practical module.

conduction band.

The so-called solar cells sensitized by a dye are a type of hybrid devices that have reached a higher degree of development so far. Within his field, porphyrins represent a very interesting alternative because there is efficient model harnessing sunlight. These systems can be synthetized in bulk heterojunction (BHJ) organic solar cells. The interaction of macrocycles with metal ions such as: Fe2+, Fe3+, Co2+, Co3+, Ni2+, Zn2+, Cu2+, Ru2+, Pd2+ and Pt2+ and hydrogen, alkyl, cycloalkyl, cyclohexyl, cycloheptyl, cyclooctyl, haloalkyl, perhaloalkyl, ether chains have permitted the stabilizations of promising new collections. In dye-sensitized solar porphyrin-based push-pull.

photosensitizers have demonstrated their potential as large and rigid planar conjugated structures, which enhance p-electron delocalization and promote intermolecular π-π interaction, as well charge transport in devices. A problem that they can presents is the effect by lack of light-harvesting beyond 850 nm, thus limiting their cell performance. In the papers, it has been reported that 50% of the total solar phonon flux is located in the red and near-infrared spectra. Zhu and colleagues had reported in 2016 that is quite urgent to develop efficient NIR absorbing molecules for high performance organic solar cells. In the next table, the authors show different publications about the development of new bioinspired porphyrin materials (**Table 2**).

#### **1.3 Metal-free organic dyes**

The DSSC free organic dyes are sensitized molecules whose perspective are aimed at staking, on top of one other in order to obtain panchromatic absorption. **Table 3** shows azo, cyano, thiophene, and carbonyl with highly conjugated. A PCE value at 14.7 has been reported by Kakiag et al. [49]. The PCE increase with Voc and Jsc and the best properties were associated with carboxylic group and highly polarizability in the presence of nitrile group.

The extension of the conjugated chain and the substitution of the thiophene groups do not represent a marked difference that allows concluding a relationship between the photovoltaic properties and the structure.

Therefore, this article reports the bibliographic revision for these compounds, specifying the following parameters: Chemical name, abbreviation, structure, power conversion efficiencies (PCE), Jsc (short-circuit-current), Voc (open circuit voltage) electrolyte used and authors.

**Chemical name Author's**


 bipyridine)(Ligand-11)(NCS)2])

— **C106**

— **GS3**

— **NCSU-10**

— **Complex**

— **[Ru]2**

— **[Ru]3**

*Ruthenium complexes for DSSC [26–33].*

*—, it is not mentioned in the article.*

**Table 1.**

**123**

**16**

TBA(Ru[(4 carboxylic acid-40

carboxylate-2,20

**designation**

*DOI: http://dx.doi.org/10.5772/intechopen.92268*

**CYC-B11**

**Structure PCE**

COO N(C4H9)4

Ru N N N N NCS NCS

> S S

Ru N N N N

> S S

Ru N

N N

> Ru N

COOH

N N

C S C S

N N

N

N

N N

N

COOH

HOOC

Ru N

N O S O

N N

S C

HO O

N

N

N

HO <sup>O</sup>

Ru Ph2P Ph2P PPh2 PPh2

Ru Ph2P Ph2P PPh2 PPh2

N S N CN

N S N

S

CO2H

CN CO2H

C6H13

COOH

NCS NCS

C6H13

HOOC

S

HOOC

S

S

C6H13

HOOC

N

HOOC

S

*Ligands and Coordination Compounds Used as New Photosensitized Materials…*

C6H13

**(%)**

COOH 2.79 9.78 435 I3/I�

**Jsc (mA/cm<sup>2</sup> ) Voc (mV)**

11.5 20.05 743 I3/I�

11.7% 19.8 758 I3/I�

8.34 18.2 703 I3/I�

1.26 4.53 496 I3/I�

6.45 13.48 650 —

5.23 11.77 598 —

**Electrolyte**

#### **Table 1.**

*Ruthenium complexes for DSSC [26–33].*

**Chemical name Author's**



tetrabutylammonium


dicarboxylato) ruthenium(II)

[(C4H9)4 N]3 [Ru- (Htcterpy)(NCS)3] (tcterpy) 4,4<sup>0</sup>

tricarboxy-2,2<sup>0</sup>

terpyridine

*cis*-Ru (4,4<sup>0</sup> dicarboxylic acid-2,

dinonyl-2,2<sup>0</sup> bipyridine)(NCS)2



20

cis-

(2,2<sup>0</sup>

4,4<sup>0</sup>

N1<sup>0</sup>

**122**

Bis(isothiocyanato)

dicarboxylato)(4,4<sup>0</sup>

ruthenium(II), Ruthenate(2�), [[2,2<sup>0</sup>

bis(5-hexyl-2 thienyl)- 2,2<sup>0</sup>

bis(5-hexylthiophen-2-yl)-2,2<sup>0</sup>





]bis(thiocyanato-N)-, hydrogen (1:2)


][4,4<sup>0</sup> -



,4″-

,2″-


dicarboxylato) ruthenium(II)

*cis*-Bis (isothiocyanato)bis

(2,20

Di-

*cis*-bis (isothiocyanato)bis

(2,20

**designation**

*Stability and Applications of Coordination Compounds*

**N3**

**N719**

**Black dye**

**Z907**

**C101**

**Structure PCE**

NCS NCS

Ru N N N

N

COOH

Ru

NCS NCS

N

COOH

NCS NCS 3 nBu4N

NCS

Ru N N

CO2

N

CO2

N N

Ru

NCS NCS

N

C9H19

COOH

Ru N N N

NCS NCS

N

S C6H13

N

N N

N

HOOC

R

HO2C

C9H19

HOOC

S

C6H13

HOOC

R

HOOC

**(%)**

**Jsc (mA/cm<sup>2</sup> ) Voc (mV)**

COOH 10.3 7.9 660 I3/I�

COOH 11.18 17.73 846 I3/I�

<sup>3</sup> 10.4 20 720 I3/I�

COOH 9.5 12.5 730

11 17.9 778 I3/I�

**Electrolyte**

**Chemical name**

— **SM 315**

— **A4**

— **A6**

— **A7**

— **A8**

— **ZnT(Mes)**

**125**

**P(CN-COOH)**

**Author's designation**

*DOI: http://dx.doi.org/10.5772/intechopen.92268*

HOOC

**Structure PCE**

OC6H13

OC6H13

OC6H13

N N

N N S

*Ligands and Coordination Compounds Used as New Photosensitized Materials…*

N N

N N

Ru N

N N

NCS NCS

N COOH

Ru N

N N

COOH

NCS NCS

N COOH

N N ZnN

> N N

COOH

N N

N N

C(CH3)3

C(CH3)3

N N N N Zn

Ph

(H3C)3C

Ph

N N Zn

C(CH3)3

CN COOH

N Z N n

N Z N n

N N Zn N N

N N Zn

N

OC8H17 C8H17O OC6H13

N COOH

<sup>C</sup> OC8H17 8H17O

**(%)**

**Jsc (mA/cm<sup>2</sup> ) Voc (mV)**

13 18.1 910

0.05 0.09 330

0.28 0.83 480

0.38 1.33 450

0.05 0.26 370

3.15 7.8 575

On the other hand, in this research also have been reported the theoretical studies towards the effect the spacer molecule in macrocycles. The linear molecule


*Ligands and Coordination Compounds Used as New Photosensitized Materials… DOI: http://dx.doi.org/10.5772/intechopen.92268*

On the other hand, in this research also have been reported the theoretical studies towards the effect the spacer molecule in macrocycles. The linear molecule

<sup>C</sup> OC8H17 8H17O

N N

N N Zn

N

OC8H17 C8H17O OC6H13

**Chemical name**

— **YD2**

— **YD2-o-C8**

— **GY21**

— **GY50**

— **SM371**

**124**

**Author's designation**

HOOC

*Stability and Applications of Coordination Compounds*

HOOC

N N S

> N N S

HOOC

HOOC

HOOC

**Structure PCE**

C6H13

C6H13

C6H13

C6H13

C6H13

C6H13

C6H13

C6H13

N N

*t* - Bu *t* - Bu

> N N

N N

*t* - Bu *<sup>t</sup>* - Bu

> N N Zn <sup>N</sup>

N N Zn

N N Zn

N

<sup>C</sup> OC8H17 8H17O

N N

N N Zn

N

OC6H13

OC6H13

OC6H13

<sup>C</sup> OC8H17 8H17O

OC8H17 C8H17O

N

<sup>C</sup> OC8H17 8H17O

OC8H17 C8H17O

OC8H17 C8H17O

**(%)**

**Jsc (mA/cm<sup>2</sup> ) Voc (mV)**

10.9 18.6 770

12.3 17.3 965

2.5 5.03 615

12.75 18.53 885

12 15.9 960

**Chemical name Author's**

2-Cyano-7-(1,1,6,6 tetramethyl-10-oxo-2,3,5,6-tetrahydro-1H,4H,10H-11-oxa-3a-aza-benzo[de] anthracen-9-yl) hepta-2,4,6-trienoic

2-Cyano-5-(1,1,6,6 tetramethyl-10-oxo-2,3,5,6-tetrahydro-1H,4H,10H-oxa-3aaza-benzo[de] anthracen-9-yl) penta-2,4-dienoic acid

2-Cyano-3-[5<sup>0</sup> - (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<sup>0</sup>

bithiophenyl-5-yl] acrylic acid

2-cyano-3-{5<sup>0</sup>

5-[[4-[4-(2,2- Diphenylethenyl) phenyl]-1,2,3,3a,4,8bhexahydrocyclopent [*b*]indol-7-yl] methylene]-2-(3 octyl-4-oxo-2-thioxo-5-thiazolidinylidene)- 4-oxo-3 thiazolidineacetic acid

2-Cyano-3-{5<sup>0</sup>

[N,N-bis(4-(2 ethylhexyloxy) phenyl)amino] phenyl}-3,4 ethylenedi -oxythiophene-5-yl}-3,3<sup>0</sup>


bithiophene-5-yl} acrylic acid

**127**



**— C218**

acid

**designation**

*DOI: http://dx.doi.org/10.5772/intechopen.92268*

**NKX-2586**

**NKX-2311**

**NKX-2677**

**NKX-2883**

**D205**

**C219**

]

**— D5**


] bithiophenyl-5-yl} acrylic acid

**Structure PCE**

CN COOH

CN COOH

> CN COOH

N O O

*Ligands and Coordination Compounds Used as New Photosensitized Materials…*

N O O

<sup>S</sup> <sup>S</sup>

S

<sup>S</sup> <sup>S</sup> CN

COOH CN

> CN COOH

N O O

N

N O O

N

N O

> N O

O

O

S N O OH O

N S O S

O O

S S Si

S S

NC <sup>S</sup>

COOH

COOH NC

**(%)**

**Jsc (mA/cm<sup>2</sup> ) Voc (mV)**

3.5 15.1 470 —

6.0 14.0 600 —

7.7 14.3 730 —

5.1 11.9 660 —

7.3 16.90 580 —

9.52 18.7 710 Ionic-

8.9 17.94 770 I3/I�

8.95 15.8 768 I3/I�

liquid

**Electrolyte**

**Table 2.** *Porphyrins for DSSC [34–40].*

designed was a benzothiophene derivate (T) and the spacer selected were *o*- *m* or *pdiphenyldiamine*. The spacer represented the communication channel between linear chains, denominated T. The stabilization of the macrocycles depends of the good assembly. The authors reported a study relationship with the photovoltaic properties for three macrocycles in function of isomeric effect in the spacer. The calculations were performed using Gaussian 09 16-18, program with B3LYP functional [58–61] and 6-31-6 (d, 2p) as basis set [64] in order to investigate the molecular geometry, electronic structures, and optical properties of *o*-PDT, *m*-PDT and *p*-PDT (**Figure 1**).

The stationary point was estimated with level of theory reported previously for the authors [64]. Finally, the authors through the Lewis acid incorporation showed an electronic improvement mechanism. The acid Lewis effect, as evaluated considering the tetracoordinated mode around metal center (**Figure 2**).

*Ligands and Coordination Compounds Used as New Photosensitized Materials… DOI: http://dx.doi.org/10.5772/intechopen.92268*


designed was a benzothiophene derivate (T) and the spacer selected were *o*- *m* or *pdiphenyldiamine*. The spacer represented the communication channel between linear chains, denominated T. The stabilization of the macrocycles depends of the good assembly. The authors reported a study relationship with the photovoltaic properties for three macrocycles in function of isomeric effect in the spacer. The calculations were performed using Gaussian 09 16-18, program with B3LYP functional [58–61] and 6-31-6 (d, 2p) as basis set [64] in order to investigate the

**Structure PCE**

CN COOH **(%)**

**Jsc (mA/cm<sup>2</sup> ) Voc (mV)**

1.72 4.3 580

0.73 2.26 530

1.54 3.98 550

molecular geometry, electronic structures, and optical properties of *o*-PDT, *m*-PDT

ering the tetracoordinated mode around metal center (**Figure 2**).

The stationary point was estimated with level of theory reported previously for the authors [64]. Finally, the authors through the Lewis acid incorporation showed an electronic improvement mechanism. The acid Lewis effect, as evaluated consid-

and *p*-PDT (**Figure 1**).

**Chemical name**

— **ZnT(4-t-**

— **ZnPc1**

— **TT1**

*—, it is not mentioned in the article.*

*Porphyrins for DSSC [34–40].*

**Table 2.**

**126**

**Author's designation**

**Bu)P(Ph2) (CN-**

**COOH)** <sup>N</sup>

*Stability and Applications of Coordination Compounds*

N N N Zn

Zn N N N N N

O O

O O

Zn N N N N N

N

N N

N

OH O

OH O

N N

O O


**Chemical name Author's**

— **KNS-1**

— **KNS-2**

— **JM-2**

3-(5-((3,6-bis(bis(4 methoxyphenyl) amino)-9H-fluoren-9 ylidene)methyl) thiophen-2-yl)-2 cyanoacrylic acid



bithiophen-5-yl)-2 cyanoacrylic acid

bithiophen]-5-yl)-2 cyanoacrylic acid



— **O4T**

— **ST4**

— **P2**

3-(5<sup>0</sup>

3-(5<sup>0</sup>

**129**

**designation**

*DOI: http://dx.doi.org/10.5772/intechopen.92268*

**TK-4**

**TK-5**

**TK-6**

— **LS-385** <sup>N</sup>

— **LS-386** <sup>N</sup>

<sup>S</sup> C6H13

<sup>S</sup> C6H13 2

2

*Ligands and Coordination Compounds Used as New Photosensitized Materials…*

**Structure PCE**

N S S COOH

N

2

N

2

S

N OCH3

H3CO N

N OCH3

> N OC8H17

S S S S S O O Oct Oct

S S S S S S S Oct Oct

S

O

C8H17O N

H3CO N

H3CO

C8H17O

*n*-

*n*-

S O

H3CO

N S

CN S S HOOC CN

> S CN COOH

OCH3

S

S

S NC COOH

NC

NC

H NC O

H NC O

OC8H17

Hex COOH

Hex COOH

S N

O OH

S N

S OH

N Cd N H2N NH2 OOCH3C CH3COO NC CN

S NC COOH

OCH3

S C6H13

S C6H13

**(%)**

COOH CN

**Jsc (mA/cm<sup>2</sup> ) Voc (mV)**

2.01 4.93 600 Co2+/Co3+

2.95 6.92 650 Co2+/Co3+

6.5 14.4 620 I3/I�

5.9 13.29 667 —

7.5 17.85 653 —

7.8 17.19 663 —

5.07 10.7 630 —

6.73 14.4 640 —

2.18 4.85 680 —

2.68 6.33 582 I3/I�

2.69 6.53 561 I3/I�

**Electrolyte**


*Ligands and Coordination Compounds Used as New Photosensitized Materials… DOI: http://dx.doi.org/10.5772/intechopen.92268*

**Chemical name Author's**



— **C228**

— **C228**

— **C229**

— **C229**

,4<sup>0</sup> dihexyloxybiphenyl-4-yl)amino-]phenyl}-

3-{6-{4-[bis (2<sup>0</sup>

hexyl-cyclopenta-[2,1-

]dithiphene-2 yl}-2-cyanoacrylic acid

— **ADEKA-1**

— **LEG 4**

4,4-di-

b:3,4-b<sup>0</sup>

**128**

2-cyano-3-[5<sup>0</sup>

tetramethyl-10-oxo-2,3,5,6-tetrahydro-1H,4H,10H-11-oxa-3a-aza-benzo[de] anthracen-9-yl)- [2,1,3-

benzothiadiazole]-4 thiophen-2-yl]-acrylic

tetramethyl-10-oxo-2,3,5,6-tetrahydro-1H,4H,10H-11-oxa-3a-aza-benzo[de] anthracen-9-yl)- [2,1,3-

benzothiadiazole]-4- (3,4-ethylene dioxythiopheneyl-5 yl)]-acrylic acid

acid

2-cyano-3-[5<sup>0</sup>

**designation**

*Stability and Applications of Coordination Compounds*

**HKK-CM4**

**HKK-CM5**

**Structure PCE**

CN COOH

> CN COOH

> > COOH NC

> > COOH NC

> > > COOH NC

COOH NC

> CN COOH

> > Si OMe OMe OMe

O OH

<sup>S</sup> <sup>S</sup>

<sup>S</sup> <sup>S</sup>

S S

S S

<sup>S</sup> <sup>S</sup> <sup>S</sup> <sup>S</sup>

<sup>S</sup> <sup>S</sup> <sup>S</sup> <sup>S</sup>

O

S CN O N H

S S

C6H13

S S OC C6H13 C6H13 4H9

N

O O

N O O

N O O

N O

N O

N O

> N O

O

O

O

O

O O

S

C6H13 S C6H13

N

OC4H9 OC4H9

C6H13

N S

C4H9O

**Y123** <sup>O</sup>

S N N

S N

**(%)**

<sup>N</sup> 5.97 14.3 580 —

**Jsc (mA/cm<sup>2</sup> ) Voc (mV)**

5.03 13.3 560 —

4.7 7.6 830 Co2+/Co3+

4.4 7.78 760 I3/I�

9.4 15.3 850 Co2+/Co3+

6,7 15.20 680 I3/I�

12.3 17.7 935 Co2+/Co3+

11.2 19.11 783 I3/I�

CN 14.7 9.55 776 I3/I�

**Electrolyte**


**2. Material and methods**

— **N, N**<sup>0</sup>

*—, it is not mentioned in the article.*

**Table 3.**

**Chemical name Author's**

— **BD-5**

— **Dendrimer**

**designation**

*DOI: http://dx.doi.org/10.5772/intechopen.92268*

**1**

— **4a** <sup>N</sup> <sup>S</sup> <sup>N</sup>

— **4b** <sup>N</sup> <sup>S</sup> <sup>N</sup>

**-**

*Structures associated with metal-free organic dyes [41–63].*

To explore and understand the electronic and optoelectronic properties of photosensitized materials with application in OPV technology, many theories have emerged. One of the most important and common theories is the theory of functional density (DFT), which is a tool that allowed to establish any property used in photosensitized materials, quantum state of atoms, molecules and solids, making modeling and simulation possible of complex systems with millions of degrees of freedom. At present, DFT has grown tremendously and has become one of the main tools in theoretical physics and molecular chemistry. Modeling in the framework of computational chemistry of photosensitized systems made up of electron donors and electron acceptors ultimately influences photo induced electron transfer and energy reactions. Numerous studies using the Density Functional Theory (DFT) methodology to design, evaluate and predict photovoltaic properties of photoactive materials with application in OPV have been published. The approximation of the theory of functional density (DFT) implemented was Gaussian 09 together with the functional correlation (B3LYP) and the base set 6-31g (d, 2p). This calculation allows optimization of geometry without symmetry restrictions for stationary points. In addition, it provided information on the harmonic frequency analysis, which allows the optimized minimum to be verified. The local minimum is identified when the number of imaginary 32fre-

**Structure PCE**

S O O

S CN

S CN COOH <sup>N</sup>

COOH

COOH NC

S S S

N

S O N

COOH <sup>S</sup> <sup>S</sup>

<sup>S</sup> <sup>S</sup> <sup>N</sup> O O N

S S S

S O O

*Ligands and Coordination Compounds Used as New Photosensitized Materials…*

HOOC CN

**PABA** <sup>N</sup> N

**(%)**

**Jsc (mA/cm<sup>2</sup> ) Voc (mV)**

5.34 12.23 680 I3/I�

5.19 13.00 675 I3/I�

0.95 2.60 500 —

4.51 9.36 630 —

1.00 2.72 537 I3/I�

**Electrolyte**

The analysis of the changes in electron density for a given electronic transition was based on the electron density difference maps (EDDMs) constructed using the GaussSum suite of programs. Gásquez and co-workers had proposed two different electronegativities (X) for the charge transfer process: one that describes fractional

**2.1 Method theoretical**

quencies is equal to zero.

**131**


*Ligands and Coordination Compounds Used as New Photosensitized Materials… DOI: http://dx.doi.org/10.5772/intechopen.92268*

#### **Table 3.**

**Chemical name Author's**

— **TA1**

— **TA2**

— **TA3**

— **TA4**

(Z)-2-cyano-3-(5″- ((E)-2,4,6 trimethoxystyryl)-

2-((Z)-4-oxo-2 thioxo-5-((5″-((E)- 2,4,6 trimethoxystyryl)-

— **D6**

— **D7**

— **SP1**

— **SP3**

— **SP4**

— **BD-3**

**130**

[2,2<sup>0</sup> :50 ,2″ terthiophen]-5-yl) acrylic acid

[2,2<sup>0</sup> :50 ,2″ terthiophen]-5-yl) methylene) thiazolidin-3-yl) acetic

acid

**designation**

*Stability and Applications of Coordination Compounds*

— **LS-387** <sup>N</sup>

**Structure PCE**

H NC O

NC COOH

NC COOH

NC COOH

NC COOH

S N O S

COOH

C6H13O 4.7 8.6 793 Co2+/Co3+

S

S

N S S NC COOH

N S S

N N

N N

N N O O

> N N

N Ph Ph <sup>N</sup>

NC HOOC

N

N S HOOC <sup>O</sup> S N S O

C6H13O

C6H13O

C6H13O CN

Br

S COOH

S

S CN COOH

Ph Ph

N Ph Ph <sup>S</sup>

> N Ph Ph <sup>S</sup>

> > COOH

N N

S S S S O O

N NC <sup>S</sup> <sup>N</sup>

S N

N OH

N N

N N

N N

> N N

S O O O

S O O O

N

N O

N

N O

O

**MR-5** <sup>N</sup>

**MR-6** <sup>N</sup>

O

**(%)**

**Jsc (mA/cm<sup>2</sup> ) Voc (mV)**

5.61 13.26 595 I3/I�

2.56 5.40 662 —

3.45 6.83 704 —

3.69 7.81 654 —

4.78 9.92 662 —

6.03 15.27 610 —

3.2 8.7 560 —

4.0 8.2 768 Co2+/Co3+

0.86 2.59 625 —

0.43 2.31 532 —

0.58 0.78 290 —

5.46 12.21 680 I3/I�

**Electrolyte**

*Structures associated with metal-free organic dyes [41–63].*
