近日，吉林大学的宋宏伟与大连民族大学的徐文等人合作并取得一项新进展。经过不懈努力，他们提出一种用于增强硅太阳能电池光收集的多波段近红外上转换核壳设计。相关研究成果已于2024年11月25日在国际知名学术期刊《光：科学与应用》上发表。

本研究报道了一种基于Ln³⁺/Yb³⁺共掺杂核壳结构上转换纳米颗粒（Ln/Yb-UCNPs，其中Ln³⁺=Ho³⁺, Er³⁺, Tm³⁺）的高效多波段上转换系统设计。在该设计中，Ln³⁺离子被掺入Ln/Yb-UCNPs的不同层中，作为不同光谱范围内的近红外（NIR）吸收剂。此设计实现了在1100至2200纳米范围内的宽谱多波段吸收，总带宽约为500纳米。研究人员发现了一种涉及Yb³⁺离子的合成电子泵浦（SEP）效应，该效应由Yb³⁺?与其他Ln³⁺离子（Ho³⁺, Er³⁺, Tm³⁺）之间的能量传递和交叉弛豫的协同作用所促进。

这种SEP效应通过有效地将电子从Ln³⁺的低激发态转移到Yb³⁺的激发态，增强了纳米材料的上转换效率，从而在硅太阳能电池（SSCs）的最佳响应区域内产生了强烈的~980纳米Yb³⁺发光，显著提升了SSCs的整体性能。集成了具有多波段激发特性的Ln/Yb-UCNPs的SSCs展现出了最宽达2200纳米的近红外响应范围，并且在标准AM 1.5G辐照下，实现了目前报道中最高的绝对光伏效率提升，增加了0.87%（总效率达到19.37%）。本研究解决了UCNP耦合SSCs的瓶颈问题，并为扩展SSCs的近红外响应范围提供了一种可行的方法。

据悉，探索镧系元素的光上转换（UC）已成为一种有前景的策略，用以拓宽硅太阳能电池（SSCs）的近红外（NIR）响应区域。然而，传统材料狭窄的近红外激发带宽和低上转换效率阻碍了其在正常阳光条件下的实际应用。

附：英文原文

Title: A multiband NIR upconversion core-shell design for enhanced light harvesting of silicon solar cells

Author: Wang, Yue, Xu, Wen, Liu, Haichun, Jing, Yuhan, Zhou, Donglei, Ji, Yanan, Widengren, Jerker, Bai, Xue, Song, Hongwei

Issue&Volume: 2024-11-25

Abstract: Exploring lanthanide light upconversion (UC) has emerged as a promising strategy to enhance the near-infrared (NIR) responsive region of silicon solar cells (SSCs). However, its practical application under normal sunlight conditions has been hindered by the narrow NIR excitation bandwidth and the low UC efficiency of conventional materials. Here, we report the design of an efficient multiband UC system based on Ln³⁺/Yb³⁺-doped core-shell upconversion nanoparticles (Ln/Yb-UCNPs, Ln³⁺=Ho³⁺, Er³⁺, Tm³⁺). In our design, Ln³⁺ ions are incorporated into distinct layers of Ln/Yb-UCNPs to function as near-infrared (NIR) absorbers across different spectral ranges. This design achieves broad multiband absorption withtin the 1100 to 2200nm range, with an aggregated bandwidth of ~500nm. We have identified a synthetic electron pumping (SEP) effect involving Yb³⁺ ions, facilitated by the synergistic interplay of energy transfer and cross-relaxation between Yb³⁺ and other ions Ln³⁺ (Ho³⁺, Er³⁺, Tm³⁺). This SEP effect enhances the UC efficiency of the nanomaterials by effectively transferring electrons from the low-excited states of Ln³⁺ to the excited state of Yb³⁺, resulting in intense Yb³⁺ luminescence at ~980nm within the optimal response region for SSCs, thus markedly improving their overall performance. The SSCs integrated with Ln/Yb-UCNPs with multiband excitation demonstrate the largest reported NIR response range up to 2200nm, while enabling the highest improvement in absolute photovoltaic efficiency reported, with an increase of 0.87% (resulting in a total efficiency of 19.37%) under standard AM 1.5G irradiation. Our work tackles the bottlenecks in UCNP-coupled SSCs and introduces a viable approach to extend the NIR response of SSCs.

DOI: 10.1038/s41377-024-01661-5

Source: https://www.nature.com/articles/s41377-024-01661-5