Investigation of the morphology and electrical characteristics of hybrid blends based on poly(3-hexylthiophene) and colloidal CuInS₂ nanocrystals of different shapes

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• 作者：Nikolay Radychev ; ^{nicolay.radychev@uni-oldenburg.de} ; Dorothea Scheunemann ; Marta Kruszynska ; Katja Frevert ; Rany Miranti ; Joanna Kolny-Olesiak ; Holger Borchert ; Jü ; rgen Parisi
• 关键词：Hybrid solar cells ; CuInS2 ; Surface modification ; Ligand exchange ; Copper indium sulfide ; Cyclic voltammetry
• 刊名：Organic Electronics
• 出版年：2012
• 出版时间：December, 2012
• 年：2012
• 卷：13
• 期：12
• 页码：3154-3164
• 全文大小：1619 K

文摘

Colloidally synthesized CuInS₂ nanocrystals are a promising candidate for hybrid solar cell applications due to suitable optical and transport properties of copper indium disulfide and being it an eco-friendly material. However, as opposite to solar cells where CuInS₂ is synthesized in situ in a conductive polymer matrix, advances in the field of hybrid solar cells containing colloidal CuInS₂ nanocrystals that are blended after synthesis with a polymer are still negligible. Here, we report about the influence of pyridine, alkylamine, and hexanethiol stabilizing ligands on the morphology of the active layer and the electrical characteristics of solar cells based on elongated and pyramidal CuInS₂ nanocrystals blended with poly(3-hexylthiophene) (P3HT). All CuInS₂ nanocrystals used within this study had a wurtzite crystal structure as revealed by X-ray diffraction. With pyridine as ligand, the morphology was found to depend strongly on the shape of the nanocrystals. Strong agglomeration was observed in the case of elongated nanocrystals and explains the low performance of corresponding solar cells. Employment of hexanethiol as ligand resulted in an improvement of the morphology of the CuInS₂/P3HT layers and enhancement of the rectification ratio of the laboratory solar cells. Nevertheless, it was found that morphology of the active layer is not the main limiting factor in the CuInS₂/P3HT system. According to cyclic voltammetry measurements, unsuitable alignment of the energy levels for CuInS₂ nanocrystals and P3HT was observed. Taking this fact into account, appropriate donor materials for CuInS₂ based bulk heterojunctions are discussed.