南京大学谭海仁团队开发出具有改进晶粒表面钝化的全钙钛矿串联太阳能电池。相关研究成果于2022年1月17日发表在《自然》。
所有钙钛矿串联太阳能电池都有望超越单结太阳能电池的效率极限；然而，到目前为止，性能最好的全钙钛矿结构太阳能电池组的认证效率低于单结钙钛矿结构太阳能电池。为了在串联电池中获得高的光电流密度，需要一个厚的混合Pb-Sn窄带隙子电池；然而，由于Pb-Sn钙钛矿中的载流子扩散长度较短，这是一个挑战。
该文中，研究人员开发了具有长扩散长度的铵离子钝化Pb-Sn钙钛矿，使子电池具有约1.2μm的吸收体厚度。分子动力学模拟表明，在钙钛矿结晶温度下，广泛使用的苯乙基铵（PEA）阳离子仅部分吸附在表面缺陷部位。使用4-三氟甲基苯基铵（CF3-PA）可增强钝化剂的吸附，其表现出比PEA更强的钙钛矿表面钝化剂相互作用。通过在前驱体溶液中加入少量的CF3-PA，研究人员将Pb-Sn钙钛矿中的载流子扩散长度增加了2倍，达到5μm以上，并将Pb-Sn钙钛矿太阳能电池的效率提高到22%以上。
研究人员报告的钙钛矿串联太阳能电池的认证效率为26.4%，超过了性能最好的单结钙钛矿太阳能电池。封装串联设备在环境条件下，在一倍太阳光强照射下，在最大功率点下运行600小时后，保持90%以上的初始性能。
附：英文原文
Title: All-perovskite tandem solar cells with improved grain surface passivation
Author: Lin, Renxing, Xu, Jian, Wei, Mingyang, Wang, Yurui, Qin, Zhengyuan, Liu, Zhou, Wu, Jinlong, Xiao, Ke, Chen, Bin, Park, So Min, Chen, Gang, Atapattu, Harindi R., Graham, Kenneth R., Xu, Jun, Zhu, Jia, Li, Ludong, Zhang, Chunfeng, Sargent, Edward H., Tan, Hairen
Issue&Volume: 2022-01-17
Abstract: All-perovskite tandem solar cells hold the promise of surpassing the efficiency limits of single-junction solar cells1–3; however, until now, the best-performing all-perovskite tandems have exhibited lower certified efficiency than have single-junction perovskite solar cells4,5. A thick mixed Pb-Sn narrow-bandgap subcell is needed to achieve high photocurrent density in tandems6; yet this is challenging owing to the short carrier diffusion length within Pb-Sn perovskites. Here we develop ammonium-cation-passivated Pb-Sn perovskites with long diffusion lengths, enabling subcells having an absorber thickness of ~1.2 μm. Molecular dynamics simulations suggest that widely-used phenethylammonium (PEA) cations are only partially adsorbed on the surface defective sites at perovskite crystallization temperatures. The passivator adsorption is predicted to be enhanced using 4-trifluoromethyl-phenylammonium (CF3-PA), which exhibits a stronger perovskite surface-passivator interaction than does PEA. By adding a small amount of CF3-PA into precursor solution, we increase the carrier diffusion length within Pb-Sn perovskites by 2x, to over 5 μm, and increase the efficiency of Pb-Sn perovskite solar cells to over 22%. We report a certified efficiency of 26.4% in all-perovskite tandem solar cells, exceeding that of the best-performing single-junction perovskite solar cells. Encapsulated tandem devices retain >90% of initial performance following 600 hours of operation at the maximum power point under one-sun illumination in ambient conditions.
DOI: 10.1038/s41586-021-04372-8
Source: https://www.nature.com/articles/s41586-021-04372-8