Performance improvement of large-area roll-to-roll slot-die-coated inverted polymer solar cell by tailoring electron transport layer

• Published in: Solar energy materials and solar cells 2014-11, Vol.130, p.191-198
• Main Authors: Cha, Hou-Chin, Huang, Yu-Ching, Hsu, Fan-Hsuan, Chuang, Chih-Min, Lu, De-Han, Chou, Cheng-Wei, Chen, Charn-Ying, Tsao, Cheng-Si
• Format: Article
• Language: English
• Subjects: Applied sciences; Azo; Coating; Electron transport; Electron transport layer; Energy; Exact sciences and technology; Inverted polymer solar cell; Nanostructure; Natural energy; Performance enhancement; Photovoltaic cells; Photovoltaic conversion; Roll-to-roll; Slot-die; Solar cells; Solar cells. Photoelectrochemical cells; Solar energy; Surficial modification; Zinc oxide
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2014.07.003

For attaining the commercialization, the large-area roll-to-roll (R2R) slot-die-coated inverted polymer solar cells (PSCs) would be promising. The electron transport layer (ETL) plays an important role in scale-up development from small PSCs. In this work, the active layer comprising poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and sol–gel zinc oxide (ZnO) ETL were slot-die coated on flexible PET/ITO substrate as reference based on the R2R process. Aluminum-doped ZnO (AZO) instead of ZnO was also adopted. For further improving the performance of large-area PSC, we used polyethylenimine ethoxylated (PEIE) material to tailor the nanostructure of ZnO and AZO ETLs for reducing the surface traps on ETLs using two approaches: (1) ZnO/PEIE bilayer formed by sequential deposition and (2) ZnO:PEIE hybrid composite as ETLs. The present work would demonstrate the optimum material (fabrication) parameters and how the performance of the R2R large-area slot-die coated PSC can be improved by modifying the ZnO- and AZO-based ETL structures. We also perform the various measurements and structural characterization to understand the relationship among R2R slot-die coating process, charge transport properties, film structure and photovoltaic performance as increasing the device areas from 1×0.3cm2 (power conversion efficiency: 2.69%) to 1×1cm2. [Display omitted] •An effective surficial modification of PEIE on ETL was used to enhance the performance of PSCs.•Both surficial modifications including of bilayer and hybrid methods improve the performance.•Performance of PSCs is analyzed by the structural characterization and photovoltaic properties.•The performance of large-area devices (1cm2) was enhanced from 1.83% to 2.43% by modifying the ETL.