Au-Nanoparticle-Embedded Open-Ended Freestanding TiO2 Nanotube Arrays in Dye-Sensitized Solar Cells for Better Electron Generation and Electron Transport

Seung-Hee Han; Won-Yeop Rho; Bong-Hyun Jun

doi:10.1021/acsomega.9b02903

Au-Nanoparticle-Embedded Open-Ended Freestanding TiO₂ Nanotube Arrays in Dye-Sensitized Solar Cells for Better Electron Generation and Electron Transport

ACS Omega. 2019 Nov 18;4(23):20346-20352. doi: 10.1021/acsomega.9b02903. eCollection 2019 Dec 3.

Authors

Seung-Hee Han¹, Won-Yeop Rho¹, Bong-Hyun Jun²

Affiliations

¹ School of International Engineering and Science, Jeonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju-si, Jeollabuk-do 54896, Republic of Korea.
² Department of Bioscience and Biotechnology, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul 05029, Republic of Korea.

Abstract

Freestanding TiO₂ nanotube arrays (TNTAs) were prepared by an electrochemical method, and dye-sensitized solar cells (DSSCs) were fabricated with the open-ended freestanding TNTAs incorporated with Au nanoparticles (NPs). Open-ended freestanding TNTAs were prepared by etching the barrier layer of closed-ended freestanding TNTAs using an ion milling method, and Au NPs were incorporated into the channel of the open-ended freestanding TNTAs by an electrodeposition method. The Au-NP-embedded open-ended freestanding TNTAs were applied to DSSCs to improve the energy conversion efficiency (ECE) by better electron generation and electron transport. The ECE of DSSCs based on the closed-ended freestanding TNTAs with Au NPs increased to 6.116% from 5.502% for DSSCs based on the closed-ended freestanding TNTAs without Au NPs, an enhancement of 11.16% because of better electron generation by the plasmonic and charging effects of the Au NPs. However, the ECE of DSSCs based on the closed-ended freestanding TNTAs incorporated with Au NPs for 40 s decreased from 6.116 to 5.336% because aggregation of the Au NPs led to a decrease in the open-circuit voltage (V _oc) and fill factor. For enhanced ECE of DSSCs, the barrier layer of closed-ended freestanding TNTAs was etched by an ion milling method for 0, 30, 60, or 90 min to provide "open-ended freestanding TNTAs". Then, Au NPs were incorporated into the open-ended freestanding TNTAs. After the barrier layer was completely removed by the ion milling method for 90 min, the ECE of the DSSCs reached 7.120% because the electron transport and electrolyte diffusion were improved by the elimination of the barrier layer of the freestanding TNTAs.