基于银纳米线透明电极的柔性碳基介孔钙钛矿太阳能电池界面研究

Solar cell which directly transfers solar energy into electric energy, is a reliable renewable clean energy technique. Organic-inorganic lead halide perovskite solar cells (PSCs hereafter) have the advantages of high power conversion efficiencies (PCEs=22.1% at AM1.5G, 100mW/cm2) and low processing costs. Low temperature processing and flexibility will further expand their application in portable consumer electronic market. Based on of the previous work done by us on both silver nanowires flexible transparent electrode and carbon-based mesoporous perovskite solar cells, we propose a kind of "flexible low-temperature perovskite solar cells based on silver nanowires electrode and conductive carbon film" in this project. We try to establish the conducting mechanism as well as transmitting behavior of AgNWs transparent electrode, on which will us assemble the flexible PSCs. Then we will try to understand the coarsening dynamics of perovskite crystallites in the mesoporous membranes, and also the interaction between perovskite crystallites and the electron/hole transporting layers (ETL/HTL) and blocking layer (BL), concretely, the role played by interfacial electronic structure on the charge extraction and the recombination kinetics across the interfaces. In order to upgrade the optoelectronic performance along with the stability of AgNWs flexible electrodes, surface modification will be carried out by using graphene film and ITO film. In order to passivate the deep traps at interface between perovskite crystallites and ETL,HBL,BL,top/bottom electrode, as well as that at surface of these crystallites, X(X=F,Cl,Br) containing molecules will be used to modify these interfaces and surfaces, which is designed to retard the recombination rate, while accelerate charge extraction rate. Finally, by improving the performance of AgNWs based transparent electrode, and tuning the interfacial processes, we aim to obtain flexible PSCs with both high efficiency and high stability, or with initial PCEs of 18% (AM1.5G, 100mW /cm2), and very slight efficiency decay of less than 5% though under continuous illumination for 2000 hours and being bent at a radius of 2mm for 5,000 times. The project will thus provide reliable theoretical and experimental fundamental knowledges for the development of flexible low-temperature PSCs.

有机-无机铅卤化物钙钛矿太阳能电池是一类新型薄膜太阳能电池，具有光电转换效率高（22.1%）、制备成本低的优点，柔性化将进一步拓展其应用。结合申请人前期研究基础，本项目设计一种基于银纳米线透明电极的柔性碳基介孔钙钛矿太阳能电池；采用石墨烯、ITO等材料对银纳米线电极进行表面修饰以提高其稳定性；采用含卤素原子X(X=F、Cl、Br)的聚合物分子与功能分子对钙钛矿晶粒表、界面进行修饰；利用修饰层与钙钛矿晶粒之间形成的Pb-X键钝化陷阱态能级，抑制电荷复合；结合所形成的MA-X键增强晶粒表界面稳定性。项目将揭示分子（离子）间化学作用强度对晶粒表、界面的电子结构、材料的稳定性以及表、界面电荷复合与萃取速率的影响机制。通过以上研究制备初始效率18%、连续光照2000小时、弯曲5000次（半径2mm）后效率衰减低于5%的原型器件，为柔性钙钛矿太阳能电池的开发提供理论与实验基础。

项目在AgNWs电极制备及透光导电机制、介孔碳基钙钛矿太阳能电池、以及器件界面等方面开展了系列研究。主要工作开展如下：.1，AgNWs电极方面，发现综合采用SnO2胶体、电镀镍、磁控溅射ITO可以银纳米线柔性透明电极的耐腐蚀性能。发现银纳米线阵列的透过率与“光偏振方向和银纳米线阵列方向夹角”以及波长有关。FDTD模拟计算表明，该行为与纳米线表面等离子体共振吸收有关。发现纳米线网络导电性决定于“银纳米线中导电通路的长度与纳米线总长度的比值”。通过数据拟合与实验验证，得到无序纳米线网格电导的决定公式。制备柔性钙钛矿太阳能电池器件，获得了8%的光电转换效率，研究了器件抗弯曲疲劳特性。.2，介孔碳基钙钛矿太阳能电池方面，采用无机胶体纳米晶作为粘接剂的碳膜为顶电极，结合真空处理促进钙钛矿前驱体在介孔骨架中的渗透和结晶，在全低温(≤150℃)条件下制备出光电转换效率为12.29%，储存稳定性达225天的低温介孔碳基钙钛矿太阳能电池。采用SnO2修饰的介孔ZrO2层替代介孔TiO2作为电子传输层，制备了效率>13%的低温介孔碳基钙钛矿太阳电池。研究了碳电极厚度、前驱体浓度对钙钛矿晶粒生长以及光电转换效率的影响规律；采用SiO2取代ZrO2作为绝缘层制备介孔钙钛矿太阳能电池。.3，器件界面方面，采用SnO2对TiO2进行表面修饰，钝化TiO2的表面缺陷，同时降低其光催化活性，提高器件工作稳定性。采用湿度辅助后退火处理对“钙钛矿晶粒/碳电极”界面进行钝化，改善界面物理接触，提升界面空穴提取速率和改善器件性能。采用PMMA掺杂Spiro-OMeTAD，改善其导电性和及其与钙钛矿活性层之间的界面接触，同时抑制了“H2O/O2/Ag”渗透扩散作用。采用辣椒素掺杂SnO2，钝化界面缺陷，抑制复合，提高器件光电转换效率与稳定性。.项目研究产出情况如下：.1，共计培养博士生4人（毕业1人），硕士生13人（毕业7人）。.2，论文专利：在Applied Physics Letters，Solar RRL等SCI源刊上发表科研论文16篇，2篇为应邀综述。受邀撰写Springer出版社书籍中的章节一篇（在审稿）；申请国家发明专利3项。