The effects of Ta 2 O 5 –ZnO films as cathodic buffer layers in inverted polymer solar cells

Ta 2 O 5 –ZnO composite films with varied composition were fabricated by sol–gel processing and applied as cathodic buffer layers (CBLs) for inverted polymer solar cells, and demonstrated enhanced power conversion efficiency with excellent stability. Physical and surface properties of Ta 2 O 5 –ZnO...

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Bibliographic Details
Published in:Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2014, Vol.2 (24), p.9361-9370
Main Authors: Lan, Jo-Lin, Cherng, Sheng-Jye, Yang, Yi-Hsun, Zhang, Qifeng, Subramaniyan, Selvam, Ohuchi, Fumio S., Jenekhe, Samson A., Cao, Guozhong
Format: Article
Language:English
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Summary:Ta 2 O 5 –ZnO composite films with varied composition were fabricated by sol–gel processing and applied as cathodic buffer layers (CBLs) for inverted polymer solar cells, and demonstrated enhanced power conversion efficiency with excellent stability. Physical and surface properties of Ta 2 O 5 –ZnO CBL films were examined by XPS, AFM, UV-Vis absorption spectra, and goniometry. It was found that CBLs incorporated with Ta 2 O 5 exert two competing impacts on the solar cell performances. On one hand, the presence of Ta 2 O 5 is likely to induce more positive charges around the Zn atom and form Ta–O–Zn bonding; it can reduce the surface charge recombination between the bulk heterojunction (BHJ) active layer and the cathodic buffer layer (CBL), and result in high power conversion efficiency; however, on the other hand an excessive amount of Ta 2 O 5 would block the pathways of charge transport and lead to a drastic reduction in power conversion efficiency.
ISSN:2050-7488
2050-7496
DOI:10.1039/C4TA01350F