基于全无机钙钛矿量子点/有机无机杂化钙钛矿双吸收层异质结的新型太阳电池设计和研究

As a result of the rapid industrial development, the world-wide energy crisis and environmental deterioration are the two most critical problems challenging human life. Solar cells is one of the most effective fundamental processes to solve both problems. As one of the most fast-developing solar cells, perovskite solar cells (PSCs) has become a hot research topic because of its high solar conversion efficiencies and low cost. However, there are still many challenges need to be solved, including fabricating high efficiency PSCs with simple device structure and achieving long-time stability. .On the one hand, several different strategies have been developed to improve the efficiency of PSCs but the obtained improvement in performance is not satisfactory. The power conversion efficiency (PCE) of solar cells is limited by the thermodynamic principles based Shockley-Queisser limit of about 33% for single junction devices. To circumvent the thermodynamic limits, series-connected tandem solar cells have been developed by stacking two or more sub-cells with complementary absorption range to broad the solar spectral coverage and better using the solar light. However, in a tandem device, the sub-cells are connected monolithically by a tunnel junction, which is rather challenging to be optimal because both energy level alignment and light transmittance need to be considered. Clearly, this causes a great challenge for the fabrication of tandem cells to achieve best performance..On the other hand, the development of PSCs was restricted by instability of organic compose in PSCs to ambient moisture. Recently, all inorganic perovskite based solar cells exhibit better environmental durability compared to organic-inorganic hybrid perovskites (OHP). However, most of inorganic perovskite materials suffer from polymorph conversion resulting in activity decay. Synthesis of inorganic perovskite quantum dots (QDs) can improve the stability of the cubic phase due to the large contribution of surface energy. However, it is hard to deposit a compact and uniform QDs film with required thickness. Therefore, it is still a challenge to achieve higher PCE of PCSs by using single inorganic perovskite QDs as light absorption layer. .As mentioned above, to prepare stable and efficient PSCs, two efficient strategies are utilizing inorganic perovskite QDs and expanding the light absorption range. However, single strategy is hard to achieve high efficiency and stability PSCs. To address these issues, combining their advantages should be an effective method. In our previous work, we proposed an interface engineering method to enhance the efficiency and stability via introducing stable α-CsPbI3 quantum dots on the top of perovskite film and achieve excellent PCE and high stability in ambient air. The work give us a hint to achieve the high efficiency and stability perovskite solar cells by utilizing the all inorganic perovskite QDs and OHP to construct heterojunction. Therefore, we further design a novel device structure of all inorganic perovskite QDs/OHP dual-absorption layer heterojunction solar cells without any tunnel junction. In this kind of device, two stacked photovoltaic layers, OHP bottom layer and inorganic perovskite QDs top layer, are fabricated using orthogonal solvents, thus direct deposit of solution-processed inorganic perovskite QDs top layer will not damage the OHP layers. As reported by previous literature, the inorganic perovskite QDs can easily achieve near-infrared (NIR) light absorption by ion doping like Sn2+ doping. Hence, in our proposed heterojunction solar cells, the OHP layer and NIR inorganic perovskite QDs layers have complementary light absorption spectra, which dramatically minimizes spectral losses. Moreover, with the high stability of coating inorganic perovskite QDs, the dual-absorption layer heterojunction solar cells would have high moist stability and thus results in high long-term stability.

钙钛矿太阳能电池的光电转换效率在短时间内便从3.8%跃升至23.7%，是目前最受关注的太阳能电池。其研究主要集中在提高电池的效率和稳定性这两个方面。其中钙钛矿叠层电池可以拓展吸收光谱提高电池效率，但制备工艺复杂难以实现大规模生产。而全无机钙钛矿量子点虽然具有高稳定性，但作为单一吸光层存在薄膜厚度不够、不均匀等问题，导致效率偏低。本项目拟结合二者的优点，开展全无机钙钛矿量子点/有机无机杂化钙钛矿双吸收层异质结太阳能电池的制备和研究工作。通过将全无机钙钛矿量子点直接旋涂在有机无机杂化钙钛矿层表面成膜的方法构筑双吸收层异质结，无需叠层电池中间的复合层，简化工艺流程。其中有机无机杂化钙钛矿层起主要吸光作用保证电池的效率，而全无机量子点则通过Sn2+掺杂实现近红外吸收，拓展光谱吸收利用范围进一步提高效率。同时全无机钙钛矿量子点具有高稳定性，可以起到隔绝水氧的作用，同时提高电池的稳定性。

本课题围绕“新型全无机钙钛矿量子点/有机无机杂化钙钛矿双吸收层异质结太阳能电池的设计和研究”这一主题，旨在通构建基于“全无机钙钛矿量子点/有机无机杂化钙钛矿双吸收层异质结”的高效和高稳定性钙钛矿太阳能电池，为钙钛矿太阳电池的广泛应用奠定技术基础。为此，本项目主要围绕钙钛矿量子点合成、钙钛矿新型组分设计钙钛矿太阳能电池表界面设计和优化等三方面核心内容展开工作。其中，钙钛矿量子点合成的相关研究解决了双吸收层异质结的吸光范围和能级匹配两大关键科学问题；钙钛矿太阳能电池表界面设计和优化的相关研究实现了钙钛矿效率瓶颈的突破；钙钛矿新型组分设计的相关研究为减少有毒铅含量，提高器件效率奠定了重要基础。因此，上述三方面研究内容是相辅相成，共同推动钙钛矿太阳电池制备及相关技术研究的快速发展。基于上述研究成果，总计发表SCI论文8篇，全部为影响因子10以上的中科院一区论文，其中包括1篇Advanced Materials、1篇Advanced Energy Materials、2篇Advanced Functional Materials、1篇ACS Energy Letters、1篇Science Bulletin、1篇Nano Energy和1篇Chemical Engineering Journal。授权国内发明专利4项，申请国内发明专利6项，申请国际发明专利1项，培养相关方向博士生1名，硕士生2名，顺利完成项目预期目标。