【Angew.Chem.】26.19%效率新突破！炔基链接剂助力高性能钙钛矿太阳能电池
通讯作者： Cheng Chen, Ming Cheng, Sang Il Seok
文章概要
引言
自组装单分子层（SAMs）已成为空穴传输层（HTL）设计的核心，通过精细调节界面分子结构可显著提升反式钙钛矿太阳能电池的能量转换效率。然而，传统的SAM分子链接剂（如烷基链或含有双键的共轭链）往往在电荷传输效率与热稳定性之间存在难以平衡的矛盾。例如，含双键的分子容易发生顺反异构化或热降解，从而导致界面电荷复合严重。本研究针对这一痛点，提出利用具有高键能、线性几何结构和强正交π键的碳碳三键（炔基，-C≡C-）作为链接剂。这种新颖的分子设计旨在通过增强π电子的离域化，在提升电荷提取速度的同时，利用其结构刚性提高电池在极端条件下的运行稳定性，为钙钛矿电池的商业化路径提供了关键的分子工程策略。
Molecular structure, dipole moments, side view, and ESP maps of (a) BT and (b) ABT; (c) Comparison of the localized ELF between BT and ABT; Total charge–density difference plots for the adsorption structures of (d) ITO/BT and (e) ITO/ABT; (f) Calculated charge–density displacement profiles along the vertical direction to the ITO surface; (g) The calculated hole and electron transfer integrals on ITO/ABT and ITO/BT interface; (h) TGA and (i) DSC curves of BT and ABT.
主要实验及结论
研究人员通过Sonogashira偶联反应成功合成了新型D–A结构的SAM分子ABT，并将其与传统结构的对照组分子BT进行了全面对比。实验结果显示，引入炔基链接剂后，分子的偶极矩显著增大至9.11 D，这有效增强了材料与ITO衬底的结合力及表面覆盖密度。通过开尔文探针力显微镜和光电子能谱分析发现，ABT能更精准地调节ITO的工作函数，使其与钙钛矿价带高度匹配，从而构建了极低的空穴提取势垒。此外，ABT分子展现出优异的热学性质，其热分解温度高达199.1°C，远超对比分子的155.7°C，这证明了炔基的刚性结构能有效抑制受热引起的分子构型扭曲。
(a) UPS spectra of SAMs-modified ITO; (b) Schematic diagram of energy level alignment; (c) XPS spectra of the In 3d core level for bare ITO and ITO covered with BT or ABT; (d) c-AFM images and corresponding surface potential distribution histogram of ITO substrates covered with BT and ABT; (e) Contact angles of perovskite precursor solution droplets on BT- and ABT-modified ITO substrates; (f) SEM images of the buried interface of perovskite films deposited on BT- and ABT-modified ITO substrates; (g) XRD patterns of perovskite films deposited on BT- and ABT-modified ITO substrates.
(a) Device architecture and (b) cross-sectional SEM image of the fabricated p-i-n PSCs; (c) Statistical box plots of VOC, JSC, FF and PCE for BT and ABT based PSC devices (20 devices per group from the same batch); J-V curves of champion devices based on different SAMs with active area of (d) 0.0625 cm2 and (e) 1.0 cm2; (f) IPCE spectrum of the champion devices based on different SAMs; (g) Thermal stability of unencapsulated PSCs measured under ISOS-D-2 protocols; (h) Operational stability under maximum power point tracking under continuous illumination in N2 atmosphere following ISOS-L-2 standards (initial efficiency of the test devices in the table).
在光伏性能验证中，基于ABT设计的反式钙钛矿太阳能电池展现了令人瞩目的表现，其冠军效率达到了26.19%，且具有高达1.184 V的开路电压和85.49%的填充因子。为了验证工业化潜力，团队制备了1.0平方厘米的大面积器件，依然保持了24.40%的高效率，效率损失远低于对照组。更为关键的是，ABT基器件在85°C持续加热2000小时后仍能保持初始效率的80.6%，而在连续光照最大功率点追踪测试中，其T80寿命超过500小时。这种卓越的稳定性源于ABT形成的致密单分子层有效阻挡了钙钛矿组分与电极之间的离子迁移，从根本上延长了器件的运行寿命。
(a) Steady-state PL spectra of perovskite films coated on SAMs substrates were extracted from (a) top surface and (b) bottom surface; (c) TRPL spectra (bottom surface), (d and e) 2D PL mapping images of perovskite film on different SAMs substrate. The incident light comes from the SAMs side; (f) Light-intensity dependence of VOC for BT-based and ABT-based devices; (g) FF S-Q limits of devices with different SAMs; (h) Mott–Schottky curves and (i) EIS curves of full devices.
总结及展望
这项工作系统地论证了在自组装单分子层中引入炔基链接剂的巨大优势。通过分子结构的微调，ABT不仅在物理层面实现了增强的π电子离域和更快的垂直空穴传输，还在化学层面提升了界面的热稳定性和抗腐蚀能力。这种“双功能”特性成功打破了传统界面材料的性能瓶颈。未来，这种基于炔基的分子设计策略有望推广到更多光电器件的界面优化中，为开发兼具高光电转换效率与超长工作寿命的新一代薄膜太阳能电池提供了极具参考价值的理论支撑和实践范本。