Author: Li, Peng
Title: TCO-free and low-cost flexible perovskite solar cells
Advisors: Zheng, Zijian (ITC)
Degree: Ph.D.
Year: 2019
Subject: Hong Kong Polytechnic University -- Dissertations
Perovskite solar cells
Solar cells -- Materials
Photovoltaic cells -- Materials
Department: Institute of Textiles and Clothing
Pages: xxii, 133 pages : color illustrations
Language: English
Abstract: The newly emerging organo-metal halide perovskite solar cells (PSCs), which was developed a decade ago, represent one of the most promising photovoltaic techniques to compete with the currently-dominating Si solar cells in the future. PSCs are characteristic of some desirable features of high efficiency, low cost, lightweight, solution processability, and so forth. Importantly, PSCs possess intrinsically excellent flexibility, stemming from sub-micrometer photo-active perovskite materials thanks to their high photo-absorption capabilities. However, flexible PSCs employing the transparent conductive oxides (TCOs) as the front electrodes often encounter severe device degradation during high degrees of mechanical deformation, as a result of the brittle TCOs. Although some transparent conductive materials based on polymers, carbons or metals have been extensively exploited to replace TCOs, many of them still suffer from inferior optoelectrical properties and/or high fabrication cost. In view of these challenges, TCO-free highly-flexible PSCs will be developed with the objectives of obtaining a high device efficiency and a low material cost at the same time in this thesis. Firstly, three types of transparent electrodes are developed by using metal grids (Au or Cu) or acid-treated PH1000 film on the flexible PET substrate. Key parameters of the metal grids and the PH1000 film have been investigated for the sake of the desired optoelectrical features. These TCO-free transparent electrodes could demonstrate satisfactory performance suitable for PSCs application. More interestingly, their high mechanical durability is potentially favorable for fabricating highly-flexible PSCs.
Next, flexible PSCs are fabricated based on the hybrid transparent electrode of Au grids and a thin layer of the conductive polymer PEDOT:PSS. The flexible device shows a champion PCE of >11%, which is comparable to the reference device on the rigid Glass/ITO substrate. Such flexible PSCs could maintain 90% and 85% of their initial efficiencies after being bent for 1000 times at a radius of 10 mm and 6 mm, respectively. Then, Cu are used both as the bottom transparent electrode as well as the top rear electrode for flexible PSCs in order to reduce the materials cost. The low-cost inorganic copper-doped nickel oxides (Cu:NiOx) are also studied and prove to be an efficient and stable hole-transporting layer (HTL) material, after treatment with methanol (MeOH). As-fabricated flexible PSCs show a champion efficiency of ~14%. When bent a radius of 5 mm for 1000 times, PCE of as-fabricated PSCs decayed only by ~10%, with negligible changes in Voc and FF. Lastly, PH1000 films deposited on PET are also exploited as the flexible transparent electrodes, upon treatment with a mild acid, methanesulfonic acid (MSA). The smoother surface and the higher optical transmittance in comparison to the metal grids-based hybrid transparent electrodes make MSA-PH1000 film a promising TCO alternative in the application for flexible PSCs. In conclusion, TCO-free transparent electrodes based on metals or polymers have been fabricated and successfully applied in the high-performance flexible PSCs, in combination with some inexpensive materials. This work may provide some insights as to how to fabricate low-cost and high-performance flexible electronic devices.
Rights: All rights reserved
Access: open access

Files in This Item:
File Description SizeFormat 
991022347056003411.pdfFor All Users5.72 MBAdobe PDFView/Open

Copyright Undertaking

As a bona fide Library user, I declare that:

  1. I will abide by the rules and legal ordinances governing copyright regarding the use of the Database.
  2. I will use the Database for the purpose of my research or private study only and not for circulation or further reproduction or any other purpose.
  3. I agree to indemnify and hold the University harmless from and against any loss, damage, cost, liability or expenses arising from copyright infringement or unauthorized usage.

By downloading any item(s) listed above, you acknowledge that you have read and understood the copyright undertaking as stated above, and agree to be bound by all of its terms.

Show full item record

Please use this identifier to cite or link to this item: