Development of carrier transport layers for efficiency enhancement of ZnO Dye-sensitized solar cells

การพัฒนาชั้นขนส่งพาหะเพื่อเพิ่มประสิทธิภาพของเซลล์แสงอาทิตย์ชนิดสีย้อมไวแสงซิงก์ออกไซด์

Name: Sutthipoj Sutthana

Classification :.DDC: 621.31244

LCSH: Dye-sensitized solar cells

LCSH: Solar cells

Abstract: Surface modification of ZnO films were demonstrated using chemical texturing processes. Firstly, ZnO films were prepared on SnO2:F substrates and modified. The modification processes consist of one-step texturing process, two-step texturing process, two-step coating-texturing process and acid vapor texturing process. After texturing process, the texturing films were characterized by FE-SEM, UV-Vis spectroscopy, BET, Raman shift, and analyze using an image processing. The films based dye-sensitized solar cells were evaluated by measuring of photovoltaic characteristics and electrochemical impedance spectroscopy. All of the texturing films from each modification processes exhibit a change in characteristics include physical property, optical property, electrochemical property. For dye-sensitized solar cells applications, the films textured by one-step texturing process with NH4OH (base solution) and HCl:HNO3:distilled water (acid solution) exhibit maximum power conversion efficiency of 2.00% and 2.02%, respectively. The power conversion efficiency is enhanced due to a formation of porous structure which is achieved better dye adsorption. Moreover, an enhanced power conversion efficiency of 2.26% is obtained for the cells fabricated with the two-step texturing films with a sequential texturing step of NH4OH and HCl:HNO3:distilled water for texturing time of 2 min and 10 s, respectively. The enhancement is related with increased dye adsorption due to a better high-ordered fine porous formation which is observed from a significant increase of small pore size in range of 5-10 nm and confirmed by maximum specific surface area. Thus, the fine porous formation is considerate an important factor for achieving dye adsorption and enhancing power conversion efficiency. For a two-step coating-texturing process, it is found that short-circuit current density is successfully increased because thickness of the films is increased and support more dye adsorption. Furthermore, fill factor is effectively improved because porous films is formed and supported better interfacial contact of ZnO/dye/electrolyte for better regeneration process. Thus, the power conversion efficiency and fill factor of 2.28% and 0.51 are observed for the two-step coating-texturing process using acid and base solution. Nevertheless, the maximum power conversion efficiency is observed of 2.35% with fill factor of 0.54 for the two-step coating-texturing process using double acid solution. Finally, a vapor texturing process is demonstrated an effective method for improving dye adsorption, increasing light scattering and reducing electron recombination which is provided an enhanced power conversion efficiency of dye-sensitized solar cells. Power conversion efficiency is enhanced related to increased short-circuit current density similar to another processes. The short-circuit current density is increased due to an increased dye adsorption which is agreed with the change in pore density. Besides, the short-circuit current density is also increased due to increased light scattering and reduced electron recombination. Therefore, this work demonstrates that surface texturing processes have ability to create appropriate porous films for achieving dye adsorption. The dye adsorption plays the significant factor for enhancing power conversion efficiency of ZnO dye-sensitized solar cells. In addition, the porous films can also improve light scattering and reduce electron recombination.

Chiang Mai University Library

Address: CHIANG MAI

Email: cmulibref@cmu.ac.th

Name: Ekasiddh Wongrat

Role: Chairman

Name: Supab Choopun

Role: Member

Name: Surachet Phadungdhitidhada

Role: Member

Name: Duangmanee Wongratanaphisam

Role: Member

Name: Pipat Ruankham

Role: Member

Created: 2016

Modified: 2019-12-23

Issued: 2019-12-23

วิทยานิพนธ์/Thesis

application/pdf

CallNumber: Th 621.31244 S967D

eng

DegreeName: Doctor of Philosophy

Level: Doctoral Degree

Descipline: Applied Physics

Grantor: Chiang Mai University

©copyrights Chiang Mai University

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