Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, Shaanxi Key Laboratory for Advanced Energy Devices, Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science & Engineering , Shaanxi Normal University , Xi'an 710119 , People's Republic of China.
School of Physical Science and Technology & Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education , Lanzhou University , Lanzhou 730000 , People's Republic of China.
Nano Lett. 2019 Mar 13;19(3):1796-1804. doi: 10.1021/acs.nanolett.8b04842. Epub 2019 Feb 27.
Recently, γ-CsPbI perovskite solar cells (PSCs) have shown potential applications in optoelectronic devices, due to their high thermal stability. However, the incomplete utilization of the solar spectra especially in the near-infrared (ca. 46%) range significantly limits the power conversion efficiency (PCE). Herein, core-shell-structured NaLuF:Yb,Er@NaLuF upconversion nanoparticles (UCNPs) have been successfully synthesized and integrated into the hole transport layer for improving PCE in γ-CsPbI PSCs. Compared with the reference one, the short-circuit current density ( J) and PCE of the optimized device reached up to 19.17 mA/cm (18.81 mA/cm) and 15.86% (15.51%), respectively. Actually, due to the ultralow photoluminescence quantum yield (PLQY, < 1%) obtained in UCNPs now, we proved the generally recognized upconversion effect of UCNPs in solar cells (adjusting the light absorption edge from the visible toward NIR range for extending the spectral absorption) was negligible. A further study found the UCNPs in the PSCs primarily served as scattering centers, which is beneficial to extend the sunlight optical path by combining with scattering and reflecting sunlight, leading to producing more photoelectric current. This study suggests a new insight into understanding the underlying mechanism of UCNPs in the PSCs and provides a promising strategy via light scattering effect to enhance the device performance.
最近，由于具有高热稳定性，γ-CsPbI 钙钛矿太阳能电池（PSCs）在光电设备中显示出潜在的应用。然而，太阳光谱的不完全利用，特别是在近红外（约 46%）范围内，显著限制了功率转换效率（PCE）。在此，我们成功合成了核壳结构的 NaLuF:Yb,Er@NaLuF 上转换纳米粒子（UCNPs），并将其集成到空穴传输层中，以提高 γ-CsPbI PSCs 的 PCE。与参考器件相比，优化后的器件的短路电流密度（J）和 PCE 分别达到了 19.17 mA/cm（18.81 mA/cm）和 15.86%（15.51%）。实际上，由于现在 UCNPs 中获得的光致发光量子产率（PLQY，<1%）非常低，我们证明了太阳能电池中普遍认可的 UCNPs 上转换效应可以忽略不计（通过将光吸收边缘从可见光调整到近红外范围来扩展光谱吸收）。进一步的研究发现，UCNPs 在 PSCs 中主要充当散射中心，这有利于通过结合散射和反射阳光来延长太阳光的光程，从而产生更多的光电电流。本研究为理解 UCNPs 在 PSCs 中的潜在机制提供了新的见解，并通过光散射效应提供了一种有前途的策略来提高器件性能。
