掺杂调控p型铜铁矿基CuMO2光阴极的能带结构及其对染料敏化太阳电池效率的影响机制

Theoretically, the efficiency of the dye-sensitized solar cells (DSCs) could be improved by replacement of the passive cathode with a photosensitive p-type semiconductor (p-SC) photocathode (giving a photoelectrochemical dye sensitized tandem cell). As yet, the open circuit voltage of the p-type DSCs is limited by the small difference in potential between the quasi-Fermi level in the p-SCs and the electrochemical potential of the redox mediator. Therefore, new p-SCs with higher conductivities and deeper valence band potentials than NiO could be certainly beneficial to build efficient p-DSCs. The valence band maximum of delafossite structure CuMO2 (M = Ga, Fe, Y) is 0.06-0.18V deeper than that of NiO. The p-type DSCs based on delafossite CuGaO2 nanoplates with saturation photovoltages exceeding 460 mV have been reported. Since CuFeO2 and CuYO2 have deeper valence band potentials and higher hole conductivities than CuGaO2, the p-DSCs with CuFeO2 or CuYO2 photocathode were expected to have higher efficiency than that of the CuGaO2 based p-DSCs. However, the p-DSCs with CuFeO2 or CuYO2 photocathode have never been studied so far. In this research, the energy band of p-type delafossite CuMO2 photocathode will be engineered via acceptor doping or/and MIII doping and its influence mechanism on the efficiency of dye sensitized solar cells will be studied. The success of this project will provide an effective method not only for exploring novel CMO photocathode, but also for improving the efficiency of p-DSCs.

理论上，用光敏p型半导体取代惰性阴极组成串联电池可以提高染料敏化太阳电池（DSCs）的效率 。但是NiO的价带顶与电解质的氧化还原电势之差较小，基于p型NiO光阴极的p-DSCs开路电压很小，因此，寻找合适能级结构的光阴极是提高电池效率的途径之一。 铜铁矿结构CuMO2（M=Ga、Fe、Y）的价带顶比NiO偏正0.06-0.18V，CuGaO2光阴极p-DSCs的开路电压达到0.46V。CuFeO2和CuYO2具有比CuGaO2更合适的价带顶位置和电输运性能，以其作为光阴极的p-DSCs有望获得更高的光电转换效率, 然而目前这方面的研究尚未见报道。因此，本项目提出以CuFeO2与CuYO2为光阴极，通过受主离子掺杂和/或MIII离子掺杂调控CMO的能带结构，分析掺杂元素和掺杂量对电池效率的影响机制。本项目将不但为新型CMO光阴极的探索提供有效的方法，也将显著提高p-DSCs的效率。

目前，p型染料敏化太阳电池（p-DSCs）中普遍使用的NiO光阴极的价带顶能级较浅，导致其p-DSCs的开路电压很难有较大幅度的提升，因此，寻找新型光阴极材料日益迫切。铜铁矿基CuIMIIIO2（M=Al，Cr，Fe等）是一类稳定的宽带隙p型半导体，在透明光电子器件领域具有潜在的应用。本项目采用甘氨酸燃烧法和水热法获得了单相CuIMIIIO2纳米粉末，通过丝网印刷法获得了纳米多孔CuIMIIIO2光阴极薄膜。通过优化薄膜厚度、烧结工艺以及Mg2+掺杂浓度，显著提高了p-DSCs的光电性能。优化后的CuFeO2光阴极平带电势达到0.69 V vs. NHE，电池的开路电压最高达到365mV。.本课题共发表论文9篇，其中SCI收录8篇，EI收录9篇，申请发明专利1项。