Lu Yongli, Shih Meng-Chen, Tan Shaun, Grotevent Matthias J, Wang Lili, Zhu Hua, Zhang Ruiqi, Lee Joo-Hong, Lee Jin-Wook, Bulović Vladimir, Bawendi Moungi G
Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, 02139, USA.
Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, 02139, USA.
Adv Mater. 2023 Nov;35(45):e2304168. doi: 10.1002/adma.202304168. Epub 2023 Oct 8.
Chemical bath deposition (CBD) is widely used to deposit tin oxide (SnO ) as an electron-transport layer in perovskite solar cells (PSCs). The conventional recipe uses thioglycolic acid (TGA) to facilitate attachments of SnO particles onto the substrate. However, nonvolatile TGA is reported to harm the operational stability of PSCs. In this work, a volatile oxalic acid (OA) is introduced as an alternative to TGA. OA, a dicarboxylic acid, functions as a chemical linker for the nucleation and attachment of particles to the substrate in the chemical bath. Moreover, OA can be readily removed through thermal annealing followed by a mild H O treatment, as shown by FTIR measurements. Synergistically, the mild H O treatment selectively oxidizes the surface of the SnO layer, minimizing nonradiative interface carrier recombination. EELS (electron-energy-loss spectroscopy) confirms that the SnO surface is dominated by Sn , while the bulk is a mixture of Sn and Sn . This rational design of a CBD SnO layer leads to devices with T ≈1500 h, a significant improvement over the TGA-based device with T ≈250 h. The champion device reached a power conversion efficiency of 24.6%. This work offers a rationale for optimizing the complex parameter space of CBD SnO to achieve efficient and stable PSCs.
化学浴沉积（CBD）被广泛用于沉积氧化锡（SnO），作为钙钛矿太阳能电池（PSC）中的电子传输层。传统配方使用巯基乙酸（TGA）来促进SnO颗粒附着在基板上。然而，据报道，挥发性的TGA会损害PSC的运行稳定性。在这项工作中，引入了挥发性的草酸（OA）作为TGA的替代品。OA是一种二元羧酸，在化学浴中作为颗粒成核和附着在基板上的化学连接剂。此外，如傅里叶变换红外光谱（FTIR）测量所示，通过热退火然后进行温和的H₂O处理，可以很容易地去除OA。协同地，温和的H₂O处理选择性地氧化了SnO层的表面，使非辐射界面载流子复合最小化。电子能量损失谱（EELS）证实，SnO表面以Sn⁴⁺为主，而体相是Sn²⁺和Sn⁴⁺的混合物。这种对CBD SnO层的合理设计导致器件的T₉₀≈1500小时，与基于TGA的器件（T₉₀≈250小时）相比有显著改善。冠军器件的功率转换效率达到了24.6%。这项工作为优化CBD SnO的复杂参数空间以实现高效稳定的PSC提供了理论依据。
