Indoline‐Based Molecular Engineering for Optimizing the Performance of Photoactive Thin Films |
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| Authors: | Ming Yu Jin Byung‐Man Kim Hyun Sil Jung Jun‐Hyeok Park Deok‐Ho Roh Dong Guk Nam Tae‐Hyuk Kwon Do Hyun Ryu |
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| Affiliation: | 1. Department of Chemistry, Sungkyunkwan University, Suwon, Republic of Korea;2. Department of Chemistry, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea;3. School of Molecular Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea |
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| Abstract: | New indoline dyes ( RK‐1 – 4 ) were designed with a planar geometry and high molar extinction coefficient, which provided surprising power conversion efficiency (PCE) with a thin titanium dioxide film in dye‐sensitized solar cells (DSCs). They had a difference in only alkyl chain length. Despite the same molecular structure, the performance of the respective DSCs varied significantly. Investigating the dye adsorption processes and charge transfer kinetics, the alkyl chain length was determined to affect the dye surface coverage as well as the recombination between the injected photoelectrons and the oxidized redox mediators. When applied to the DSCs as a light harvester, RK‐3 with the dodecyl group exhibited the best photocurrent density, consequently achieving the best PCE of 9.1% with a 1.8 μm active and 2.5 μm scattering layer because of the most favorable charge injection. However, when increasing the active layer thickness, overall device performance deteriorated and the charge collection and regeneration played major roles for determining the PCE. Therefore, RK‐2 featuring the highest surface coverage and moderate alkyl chain length obtained the highest PCEs of 8.8% and 7.9% with 3.5 and 5.1 μm active layers, respectively. These results present a promising perspective of organic dye design for thin film DSCs. |
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| Keywords: | alkyl chain length charge transfer kinetics dye aggregation dye‐sensitized solar cells indoline dyes |
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