Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , 21 Nanyang Link, Singapore 637371, Singapore.
ACS Nano. 2014 Oct 28;8(10):10101-10. doi: 10.1021/nn505020e. Epub 2014 Sep 15.
The origins of performance enhancement in hybrid plasmonic organic photovoltaic devices are often embroiled in a complex interaction of light scattering, localized surface plasmon resonances, exciton-plasmon energy transfer and even nonplasmonic effects. To clearly deconvolve the plasmonic contributions from a single nanostructure, we herein investigate the influence of a single silver nanowire (NW) on the charge carriers in bulk heterojunction polymer solar cells using spatially resolved optical spectroscopy, and correlate to electrical device characterization. Polarization-dependent photocurrent enhancements with a maximum of ∼ 36% over the reference are observed when the transverse mode of the plasmonic excitations in the Ag NW is activated. The ensuing higher absorbance and light scattering induced by the electronic motion perpendicular to the NW long axis lead to increased exciton and polaron densities instead of direct surface plasmon-exciton energy transfer. Finite-difference time-domain simulations also validate these findings. Importantly, our study at the single nanostructure level explores the fundamental limits of plasmonic enhancement achievable in organic solar cells with a single plasmonic nanostructure.
在混合等离子体有机光伏器件中，性能增强的起源通常涉及光散射、局域表面等离子体共振、激子-等离子体能量转移甚至非等离子体效应的复杂相互作用。为了清楚地从单个纳米结构中解卷积等离子体贡献，我们使用空间分辨光谱学研究了单个银纳米线（NW）对体异质结聚合物太阳能电池中载流子的影响，并与电设备特性相关联。当等离子体激发的横向模式被激活时，观察到与参考相比最大约 36%的偏振相关光电流增强。随后，由于电子运动垂直于 NW 长轴引起的更高的吸收率和光散射导致激子和极化子密度增加，而不是直接的表面等离子体-激子能量转移。有限差分时域模拟也验证了这些发现。重要的是，我们在单个纳米结构水平上的研究探索了在具有单个等离子体纳米结构的有机太阳能电池中实现等离子体增强的基本限制。
