Bis(tri-n-hexylsilyl oxide) Silicon Phthalocyanine: A Unique Additive in Ternary Bulk Heterojunction Organic Photovoltaic Devices

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• 作者：Beno卯t H. Lessard ; Jeremy D. Dang ; Trevor M. Grant ; Dong Gao ; Dwight S. Seferos ; Timothy P. Bender
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2014
• 出版时间：September 10, 2014
• 年：2014
• 卷：6
• 期：17
• 页码：15040-15051
• 全文大小：703K
• ISSN：1944-8252

文摘

Previous studies have shown that the use of bis(tri-n-hexylsilyl oxide) silicon phthalocyanine ((3HS)₂-SiPc) as an additive in a P3HT:PC₆₁BM cascade ternary bulk heterojunction organic photovoltaic (BHJ OPV) device results in an increase in the short circuit current (J_SC) and efficiency (畏_eff) of up to 25% and 20%, respectively. The previous studies have attributed the increase in performance to the presence of (3HS)₂-SiPc at the BHJ interface. In this study, we explored the molecular characteristics of (3HS)₂-SiPc which makes it so effective in increasing the OPV device J_SC and 畏_eff. Initially, we synthesized phthalocyanine-based additives using different core elements such as germanium and boron instead of silicon, each having similar frontier orbital energies compared to (3HS)₂-SiPc and tested their effect on BHJ OPV device performance. We observed that addition of bis(tri-n-hexylsilyl oxide) germanium phthalocyanine ((3HS)₂-GePc) or tri-n-hexylsilyl oxide boron subphthalocyanine (3HS-BsubPc) resulted in a nonstatistically significant increase in J_SC and 畏_eff. Secondly, we kept the silicon phthalocyanine core and substituted the tri-n-hexylsilyl solubilizing groups with pentadecyl phenoxy groups and tested the resulting dye in a BHJ OPV. While an increase in J_SC and 畏_eff was observed at low (PDP)₂-SiPc loadings, the increase was not as significant as (3HS)₂-SiPc; therefore, (3HS)₂-SiPc is a unique additive. During our study, we observed that (3HS)₂-SiPc had an extraordinary tendency to crystallize compared to the other compounds in this study and our general experience. On the basis of this observation, we have offered a hypothesis that when (3HS)₂-SiPc migrates to the P3HT:PC₆₁BM interface the reason for its unique performance is not solely due to its frontier orbital energies but also might be due to a high driving force for crystallization.

Keywords:

boron; germanium; silicon; phthalocyanine; ternary; cascade; bulk; heterojunction; solar; cell; photovoltaic; P3HT; PC₆₁BM