透明Cu^2S@氮掺杂碳纳米片用于双面量子点敏化太阳能电池对电极的性能

Performance of Transparent Cu2S@N-doped Carbon Film as Counter Electrode for Bifacial Quantum Dot Solar Cells

采用液相外延生长法制备了一种由铜和四羧基卟啉配位的金属–有机框架薄膜材料,以其为牺牲模板,原位合成了Cu2S和氮掺杂碳的复合透明膜(Cu2S@NCF),将其直接作双面CdS/CdSe量子点敏化太阳能电池(QDSSC)对电极,并对其进行了结构、形貌及性能研究。结果表明:Cu-(5,10,15,20-(4-羧基苯基)卟啉)(TCPP)薄膜在煅烧过程中,Cu原子在硫粉存在下转变成了Cu2S纳米颗粒,而含氮的有机连接单元TCPP原位碳化成了氮掺杂的碳。Cu2S@NCF保持了Cu-TCPP薄膜的纳米片形貌,且大量尺寸均一的Cu2S小颗粒分布于纳米片上,以其作对电极所组装的CdS/CdSe QDSSC具有优异的光伏性能,从正面辐射和背面辐射分别获得了4.16%和3.72%的光电转化效率(η),高于Pt电极组装QDSSC的η(2.39%和1.73%)。通过对循环伏安曲线、电化学阻抗谱和Tafel极化曲线分析可知,Cu2S@NCF对Sn2–离子催化还原具有传输阻抗低、扩散速率快和催化活性高等特点,以其作对电极组装的CdS/CdSe QDSSC获得了优异的光伏性能。

A copper-metalloporphy in metal-organic framework material(Cu-TCPP) was synthesized via a liquid-phase epitaxy approach. Afterward, a transparent Cu2S@N-doped carbon film was in situ fabricated using Cu-TCPP as a template, and was directly used as a counter electrode for bifacial CdS/CdSe quantum-dot sensitive solar cells(QDSSC). The morphology, construction, and performance of Cu2S@N-doped carbon film were also investigated. During the sulfidation process, the cupric ions in Cu-TCPP thin film were transformed into Cu2S nanoparticles, while the nitrogen-rich ligand(TCPP) was in situ carbonized, generating N-doped carbon and leading to the formation of a uniform Cu2S@N-doped carbon film. After the sulfidation of Cu-TCPP, the original nanosheet morphology is maintained and uniform Cu2S nanoparticles are embedded on the nanosheet surface. As a result, the transparent Cu2S@N-doped carbon film exhibits greater power conversion efficiencies(i.e., 4.16% and 3.72%) rather than Pt(i.e., 2.39% and 1.73%) from the front and rear irradiations, respectively. Based on the analysis of the systematic electrochemical data by cyclic voltammetry test, electrochemical impedance spectroscopy and Tafel test, a transparent Cu2S@N-doped carbon film with a low charge-transfer resistance, a fast ion diffusion rate, and an excellent catalytic ability is obtained for Sn2–/S2– redox reaction. As a result, the superior photovoltaic performance of bifacial CdS/CdSe QDSSC can be achieved.