Three new d⁸- and d¹⁰-configuration based 1,1′-bis-(diphenylphosphino)ferrocene (dppf) appended thiosquarates complexes with general composition [M(mtsq)₂dppf] (M = Ni²⁺ (NiL₂); Zn²⁺ (ZnL₂) and Cd²⁺ (CdL₂)) (mtsq = 3-ethoxycyclobutenedione-4-thiolate) have been synthesized and characterized spectroscopically as well as in case of NiL₂ by single crystal X-ray diffraction technique. The single crystal X-ray analysis reveals square planar geometry around Ni(II) in NiL₂, where Ni(II) coordinates with two sulfur centres of two mtsq ligands in monodentate fashion and two phosphorus of a dppf ligand in chelating mode. The supramolecular architecture of NiL₂ is sustained by intermolecular C–H⋯O interactions to form one-dimensional chain. Further, the application of these newly synthesized complexes as sensitizers and co-sensitizers/co-absorbents with ruthenium based N719 sensitizer in dye-sensitized solar cells (DSSCs) have been explored. The DSSC set-up based on NiL₂ offers best photovoltaic performance with photovoltaic efficiency (η) 5.12%, short-circuit current (J_sc) 11.60 mA cm⁻², open circuit potential (V_oc) 0.690 V and incident photon to current conversion efficiency (IPCE) 63%. In co-sensitized DSSC set-up, ZnL₂ along with state-of-the-art N719 dye displays best photovoltaic performance with η 6.65%, J_sc 14.47 mA cm⁻², V_oc 0.729 V and IPCE 69%, thereby showing an improvement by 15.25% in photovoltaic efficiency in comparison to the photovoltaic efficiency of N719 sensitized DSSC set-up. Variation in co-sensitization behaviour have been ascribed to the differences in the excited state energy level of co-sensitizers. The ZnL₂ and CdL₂ have a higher energy level position than N719 dye, allowing efficient electron transfer to N719 during light irradiation, while excited state of NiL₂ is lower than N719 dye, preventing photoexcited electron transfer to N719, resulting in its lowest overall efficiency among the three co-sensitized DSSC setups.

中文翻译：

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1,1'-双（二苯基膦）二茂铁附加d8-和d10-构型的硫代方酸盐：染料敏化太阳能电池的敏化和共敏化特性的分子和电子构型见解

三种新的基于 d ⁸ - 和 d ¹⁰ - 构型的 1,1′-双（二苯基膦）二茂铁 (dppf) 附加硫代方酸盐配合物，其一般组成为 [M(mtsq) ₂ dppf] (M = Ni ²⁺ ( NiL ₂ )； Zn ²⁺ ( ZnL ₂ ) 和 Cd ²⁺ ( CdL ₂ )) (mtsq = 3-乙氧基环丁烯二酮-4-硫醇盐) 已被合成并通过光谱以及NiL ₂的情况通过单晶 X 射线衍射技术进行表征。单晶X射线分析揭示了NiL ₂中Ni( II )周围的方形平面几何形状，其中Ni( II )以单齿形式与两个mtsq配体的两个硫中心配位，并以螯合模式与dppf配体的两个磷配位。NiL ₂的超分子结构由分子间C-H⋯O相互作用维持，形成一维链。此外，还探索了这些新合成的配合物作为敏化剂和共敏化剂/共吸收剂与钌基N719敏化剂在染料敏化太阳能电池（DSSC）中的应用。基于NiL _{2 的}DSSC 设置提供了最佳的光伏性能，光伏效率 ( η ) 为 5.12%，短路电流 ( J _sc ) 11.60 mA cm ^-2，开路电势 ( V _oc ) 0.690 V 和入射光子电流转换效率（IPCE）63%。在共敏化 DSSC 装置中，ZnL ₂与最先进的 N719 染料一起显示出最佳的光伏性能，η 6.65%、J _sc 14.47 mA cm ^-2、V _oc 0.729 V 和 IPCE 69%，从而显示与 N719 敏化 DSSC 装置的光伏效率相比，光伏效率提高了 15.25%。共敏化行为的变化归因于共敏化剂激发态能级的差异。 ZnL ₂和CdL ₂具有比N719染料更高的能级位置，允许在光照射期间有效电子转移到N719，而NiL 2_的激发态低于N719染料，阻止光激发电子转移到N719，导致其总体最低三个共同敏化 DSSC 设置之间的效率。