Constructing High-Efficiency D鈥揂鈭捪€鈥揂-Featured Solar Cell Sensitizers: a Promising Building Block of 2,3-Diphenylquinoxaline for Antiaggregation and Photostability

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• 作者：Kai Pei ; Yongzhen Wu ; Ashraful Islam ; Qiong Zhang ; Liyuan Han ; He Tian ; Weihong Zhu
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2013
• 出版时间：June 12, 2013
• 年：2013
• 卷：5
• 期：11
• 页码：4986-4995
• 全文大小：501K
• 年卷期：v.5,no.11(June 12, 2013)
• ISSN：1944-8252

文摘

Controlling the sensitizer morphology on a nanocrystalline TiO₂ surface is beneficial to facilitating electron injection and suppressing charge recombination. Given that the grafted alkyl chain on a 蟺-bridge thiophene segment for preventing 蟺 aggregation can deteriorate its intrinsic photostability, we incorporate a promising building block of 2,3-diphenylquinoxaline as the additional acceptor to construct a novel D鈥揂鈭捪€鈥揂-featured dye IQ₄, which exhibits several characteristics: (i) efficiently decreasing the molecular HOMO鈥揕UMO energy gap by extending its absorption bands; (ii) showing a moderate electron-withdrawing capability for an ideal balance in both promising photocurrent and photovoltage; (iii) endowing an ideal morphology control with strong capability of restraining the intermolecular aggregation and facilitating the formation of a compact sensitizer layer via two twisted phenyl groups grafted onto the quinoxaline unit. The coadsorbent-free dye-sensitized solar cell (DSSC) based on dye IQ₄ exhibits very promising conversion efficiency as high as 9.24 卤 0.05%, with a short-circuit current density (J_sc) of 17.55 mA cm^鈥?, an open-circuit voltage (V_oc) of 0.74 V, and a fill factor (FF) of 0.71 under AM 1.5 illumination (100 mW cm^鈥?). IQ₄-based DSSC devices with an ionic liquid electrolyte can keep constant performance during a 1000 h aging test under 1 sun at 60 掳C. Because of spatial restriction, the two phenyl groups grafted onto the additional electron-withdrawing quinoxaline are demonstrated as efficient building blocks, not only improving its photostability and thermal stability but also allowing it to be a successful antiaggregation functional unit. As a consequence, the incorporated 2,3-diphenylquinoxaline unit can realize a facile structural modification for constructing organic coadsorbent-free D鈥揂鈭捪€鈥揂-featured sensitizers, thus paving a way to replace the common, stability-deleterious grafted alkyl chain on the thienyl bridge.

Keywords:

solar cells; organic sensitizers; quinoxaline; antiaggregation; photostability