**5. Recent progress in DSSCs**

Till date, the record efficiency of DSSCs is exclusively achieved on TiO2 nanoparticles. Optimized photoelectrode films usually contain two layers: the bottom layer is a 12-μm thick transparent layer made of 10–20 nm TiO2 nanoparticles which has efficiently high surface area for dye adsorption; the top layer is a 4-μm thick film made of much larger TiO2 particles (400 nm in diameter) to scatter light back into the bottom layer and enhance near-IR light harvesting [3]. The highest efficiency achieved based on the different architecture of DSSCs is summarized in **Table 2**. Despite the excellent performance of TiO2 nanoparticle films in conventional DSSCs, they are still incapable to contribute suitable efficiency as compared to silicon based solar cells. Thus there is a need to realize a higher access rate of the photogenerated electrons from dye to the photoanode, to extend the efficiency at suitable level.

## **5.1 Important results**

The TiO2 photoanode prepared via the ion implantation method has active paths to expand the DSSC performance [19]. Ion implantation permits the incorporation of Ti4+ ion species at accelerated high-energy into the raw surface under high applied power for short time duration. On the other hand, it can improve the properties of TiO2 like enhanced resistance to oxidization, little interfacial fault and respectable optical properties [17]. But till date the reported work on ion implanted TiO2 served as photoanode in DSSC are very limited (available reports are summarized in **Table 3**). The implanted ions may act as intermediaries for charge transfer and centers for electron-hole recombination, and this dual characters affect the performance of the DSSC. The true impact should be conceded by both the effects, and also depend on the doses of the implanted ions. It has been found that the annealing state also play a key to explaining the charge transfer dynamics on ion implantation, because annealing state regulates the activation and the diffusion profile of the dopant. The beginning part of the annealing is more precarious since the in-activated dopants act as recombination sites, which reduces the minority carrier lifetime and decreases the performance of DSSCs. Luo et al. and Low et al. has found that minimum temperature annealing of ion implantation TiO2

photoanode was due to shallow emitter which can enhance the quantum efficiency

**Dopant/Modifier Strategies η (%) Ref.**

oxide nanosheet by incorporating the Ti4+ ion at various applied

and deposited onto ITO. The deposited TiO2 films have been subjected to MPII at 20 keV in order to incorporate ruthenium Ru

.

5.85 [15]

8.51 [16]

8.0 [17]

5.32 [18]

1.64 [19]

4.86 [20]

Ag-ion Tri-layer titania films has been doped with Ag ions using metal vapor vacuum arc ion-implantation.

powers ranging from 50 to 250 W

*DOI: http://dx.doi.org/10.5772/intechopen.83566*

cells is 1 <sup>10</sup><sup>15</sup> atom\*cm<sup>2</sup>

ions of fluence 1 <sup>10</sup><sup>16</sup> ions cm<sup>2</sup>

Iron Fe-doped TiO2 electrodes with the illumination of

<sup>6</sup> <sup>10</sup><sup>15</sup> atom∕cm<sup>2</sup>

*Doped/surface modified through ion implanted TiO2 based DSSCs.*

Ti Ti ion implantation has been used to modify the reduced graphene

*Modification of Physical and Chemical Properties of Titanium Dioxide (TiO2) by Ion…*

Ruthenium-iron The anatase TiO2 electrode has been prepared via a sol-gel process

and Fe atoms into the TiO2 surface layer.

Carbon The optimal concentration of ions implantation for C-implanted

Nitrogen TiO2 layer has been uniformly implanted with 100 keV nitrogen (N)

In the future, dye-sensitized solar cells will be used in many fields, such as mobile commerce, building-integrated photovoltaics (BIPVs), and vehicles. Moreover, DSSCs are essential in the Smart Grid, which are utilized in our daily lives. To apply solar energy in the Smart Grid, DSSCs are required to have transparency, flexibility, lightweight, low cost, and high power conversion efficiency. In terms of low cost and lightweight, organics, inorganics, and hybrid materials have brighter prospects than the semiconductors. In hybrid materials, photovoltaic cells have been prepared with the advantages of organics or inorganics selectively. However, it is not easy to increase the power conversion efficiency. One potential solution presented in this study is to use ion implanted TiO2 nanostructures in DSSCs. The slow progress of ion-implanted TiO2-based DSSCs in the past 7 years has demanded to realize the reliable and practical commercialization of DSSCs. It is expected that ion-implanted TiO2 can efficiently separate photoexcited charge carriers and generate higher photocurrent in DSSCs. In comparison to untreated cell, the implant ion can act as mediators for electron transport that reduces charge transfer resistance and enhance the dye loading resulting in boost of PCE [15]. One way of achieving the better light-harvesting ability is to grow the various low dimensional nanoparticles on the ion-implanted TiO2 thin film, which is presently the active field of study [17]. Thus, the future prospects of material and ideas revealed in the present chapter can be better applied to efficient visible light-activated material to

I would like to express my sincere gratitude to Mrs. Shaju Summi (Vice President) and Syed Maqbool Husain Sha-Shib Group of Institutions for their continuous

at short wavelengths [15, 16].

boost the performance of DSSCs.

**Acknowledgements**

**47**

**6. Conclusions**

**Table 3.**


### **Table 2.**

*Photovoltaic parameters of the DSSCs under an illumination of 100 mW/cm<sup>2</sup> (AM 1.5G).*

*Modification of Physical and Chemical Properties of Titanium Dioxide (TiO2) by Ion… DOI: http://dx.doi.org/10.5772/intechopen.83566*


### **Table 3.**

**5. Recent progress in DSSCs**

*Ion Beam Techniques and Applications*

efficiency at suitable level.

**5.1 Important results**

**Table 2.**

**46**

Till date, the record efficiency of DSSCs is exclusively achieved on TiO2 nanoparticles. Optimized photoelectrode films usually contain two layers: the bottom layer is a 12-μm thick transparent layer made of 10–20 nm TiO2 nanoparticles which has efficiently high surface area for dye adsorption; the top layer is a 4-μm thick film made of much larger TiO2 particles (400 nm in diameter) to scatter light back into the bottom layer and enhance near-IR light harvesting [3]. The highest efficiency achieved based on the different architecture of DSSCs is summarized in **Table 2**. Despite the excellent performance of TiO2 nanoparticle films in conventional DSSCs, they are still incapable to contribute suitable efficiency as compared to silicon based solar cells. Thus there is a need to realize a higher access rate of the photogenerated electrons from dye to the photoanode, to extend the

The TiO2 photoanode prepared via the ion implantation method has active paths to expand the DSSC performance [19]. Ion implantation permits the incorporation of Ti4+ ion species at accelerated high-energy into the raw surface under high applied power for short time duration. On the other hand, it can improve the properties of TiO2 like enhanced resistance to oxidization, little interfacial fault and respectable optical properties [17]. But till date the reported work on ion implanted TiO2 served as photoanode in DSSC are very limited (available reports are summarized in **Table 3**). The implanted ions may act as intermediaries for charge transfer and centers for electron-hole recombination, and this dual characters affect the performance of the DSSC. The true impact should be conceded by both the effects, and also depend on the doses of the implanted ions. It has been found that the annealing state also play a key to explaining the charge transfer dynamics on ion implantation, because annealing state regulates the activation and the diffusion profile of the dopant. The beginning part of the annealing is more precarious since the in-activated dopants act as recombination sites, which reduces the minority carrier lifetime and decreases the performance of DSSCs. Luo et al. and Low et al.

has found that minimum temperature annealing of ion implantation TiO2

*Photovoltaic parameters of the DSSCs under an illumination of 100 mW/cm<sup>2</sup> (AM 1.5G).*

**Author Year Dye η (%) Ref.** Kenji et al. 2015 ADEKA-1 and LEG4 14.3 [28] Simon et al. 2014 SM315 with cobalt (II/III) redox 13.0 [29] Liyuan et.al. 2012 N3 11.4 [5] Yella et al. 2011 YD2-o-C8 12.3 [11] Kim et al. 2010 Black dye 11.2 [30] Qingjiang et al. 2010 Ruthenium 12.1 [31] Chen et al. 2009 CYC-B11 dye 11.5 [32] Feifei et al. 2008 C101 and C102 11.3 [33] Yasuo et al. 2006 Black dye with YD2-o-C8 11.1 [34] *Doped/surface modified through ion implanted TiO2 based DSSCs.*

photoanode was due to shallow emitter which can enhance the quantum efficiency at short wavelengths [15, 16].

## **6. Conclusions**

In the future, dye-sensitized solar cells will be used in many fields, such as mobile commerce, building-integrated photovoltaics (BIPVs), and vehicles. Moreover, DSSCs are essential in the Smart Grid, which are utilized in our daily lives. To apply solar energy in the Smart Grid, DSSCs are required to have transparency, flexibility, lightweight, low cost, and high power conversion efficiency. In terms of low cost and lightweight, organics, inorganics, and hybrid materials have brighter prospects than the semiconductors. In hybrid materials, photovoltaic cells have been prepared with the advantages of organics or inorganics selectively. However, it is not easy to increase the power conversion efficiency. One potential solution presented in this study is to use ion implanted TiO2 nanostructures in DSSCs. The slow progress of ion-implanted TiO2-based DSSCs in the past 7 years has demanded to realize the reliable and practical commercialization of DSSCs. It is expected that ion-implanted TiO2 can efficiently separate photoexcited charge carriers and generate higher photocurrent in DSSCs. In comparison to untreated cell, the implant ion can act as mediators for electron transport that reduces charge transfer resistance and enhance the dye loading resulting in boost of PCE [15]. One way of achieving the better light-harvesting ability is to grow the various low dimensional nanoparticles on the ion-implanted TiO2 thin film, which is presently the active field of study [17]. Thus, the future prospects of material and ideas revealed in the present chapter can be better applied to efficient visible light-activated material to boost the performance of DSSCs.

### **Acknowledgements**

I would like to express my sincere gratitude to Mrs. Shaju Summi (Vice President) and Syed Maqbool Husain Sha-Shib Group of Institutions for their continuous support and encouragement throughout this work. The help rendered by Dr. Oroosa Subohi (Assistant Professor, Department of Physics, Visvesvaraya National Institute of Technology (VNIT), Nagpur, 440010, Maharashtra) is highly appreciated.

**References**

194-197

1991;**353**:737-740

2018;**11**:476-526

[1] Parra MR, Pandey P, Siddiqui H, Sudhakar V, Krishnamoorthy K, Haque FZ. Evolution of ZnO nanostructures as hexagonal disk: Implementation as photoanode material and efficiency enhancement in Al: ZnO based dye sensitized solar cells. Applied Surface

*DOI: http://dx.doi.org/10.5772/intechopen.83566*

[9] Zhang S, Yang X, Numata Y, Han L. Highly efficient dye-sensitized solar cells: progress and future challenges. Energy and Environmental Science.

[10] Wang M, Grätzel C, Zakeeruddin SM, Grätzel M. Recent developments in redox electrolytes for dye-sensitized solar cells. Energy and Environmental

[11] Yella A, Lee H-W, Tsao HN, Yi C, Chandiran AK, Nazeeruddin MK, et al. Porphyrin-sensitized solar cells with cobalt (II/III)-based redox electrolyte exceed 12 percent efficiency, M. Grätzel. Science. 2011;**334**(6056):

[12] Feng X, Zhu K, Frank AJ, Grimes CA, Mallouk TE. Rapid charge transport in dye-sensitized solar cells made from vertically aligned single-crystal rutile TiO(2) nanowires. Angewandte Chemie (International ed. in English. 2012;**124**:

[13] Lv M, Zheng D, Ye M, Xiao J, Guo W, Lai Y, et al. Optimized porous rutile TiO2 nanorod arrays for enhancing the efficiency of dye-sensitized solar cells. Energy and Environmental Science.

[14] Ye M, Chen C, Lv M, Zheng D, Guo W, Lin C. Facile and effective synthesis of hierarchical TiO2 spheres for efficient dye-sensitized solar cells. Nanoscale.

[15] Luo J, Zhou J, Guo H, Yang W, Liao B, Shi W, et al. Effects of Ag-ion implantation on the performance of DSSCs with a tri-layer TiO2 film. RSC Advances. 2014;**4**:56318-56322

[16] Low FW, Lai CW, Hamid SBA. Surface modification of reduced graphene oxide film by Ti ion

2013;**6**:1443-1464

*Modification of Physical and Chemical Properties of Titanium Dioxide (TiO2) by Ion…*

629-634

2781-2784

2013;**6**:1615-1622

2013;**5**:6577-6583

Science. 2012;**5**:9394-9405

Science. 2019;**470**:1130-1138

[2] Parra MR, Pandey P, Siddiqui H, Qadri SB, Haque FZ. New-insight into the physical properties of Zn1xBxO two-dimensional hexagonal nanodisks: An efficient material for dye sensitized solar cells. Materials Letters. 2018;**238**:

[3] O'Regan B, Gratzel M. A low-cost, high-efficiency solar cell based on dyesensitized colloidal TiO2 films. Nature.

[4] Tétreault N, Grfitzeli M. Novel nanostructures for next generation dyesensitized solar cells. Energy and

Environmental Science. 2012;**5**:8506-8516

[5] Yun S, Qin Y, Uhl AR, Vlachopoulos N, Yin M, Li D, et al. New-generation integrated devices based on dyesensitized and perovskite solar cells. Energy and Environmental Science.

[6] Ye M, Wen X, Wang M, Iocozzia J, Zhang N, Lin C, et al. Recent advances in dye-sensitized solar cells: From photoanodes, sensitizers and electrolytes to counter electrodes. Materials Today. 2015;**18**:155-162

[7] Lee C-P, Li C-T, Ho K-C. Use of organic materials in dye-sensitized solar cells. Materials Today. 2017;**20**:267-283

[8] Shaikh JS, Shaikh NS, Mali SS, Patil JV, Pawar KK, Kanjanaboos P, et al. Nanoarchitectures in dye-sensitized solar cells: Metal oxides, oxide

perovskites and carbon-based materials.

Nanoscale. 2018;**10**:4987-5034

**49**
