周期量级激光脉冲对有机太阳能电池中超快载流子行为的研究

项目名称： 周期量级激光脉冲对有机太阳能电池中超快载流子行为的研究

项目编号： No.61475169

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 无线电电子学、电信技术

项目作者： 杜鹃

作者单位： 中国科学院上海光学精密机械研究所

项目金额： 80万元

中文摘要： 有机太阳能电池相关材料和器件是近年来国内外科学研究和尖端工业技术的前沿和热点。围绕如何提高光伏电池转换效率的核心问题，越来越多的研究小组采用飞秒激光脉冲研究有机太阳能电池的工作机理。本项目将主要进行以下几方面的研究：采用可见波段周期量级激光脉冲,实时观测光生载流子的超快演变过程，探索解决有机太阳能电池中光激发初始产物存在的争议；率先采用400nm周期量级激光脉冲，研究多余光子能量对PBDTTT类窄带隙共聚物/富勒烯衍生物混膜构成的有机太阳能电池中光生载流子的超快产生、分离及传输机制的影响，探索PBDTTT分子内电荷迁移过程对有机太阳能电池转换效率的潜在催动作用。这些研究有助于将人们对有机太阳能工作机理的认识推向到更广的波长范围，有望填补目前太阳能电池的电荷分离和传递研究中的诸多空白，从而进一步对聚合物太阳能电池中器件性能进行优化，最终有望解决有机太阳能电池低能量转换效率的难题。

中文关键词： 超快激光光谱；飞秒激光；有机太阳能电池；体异质结；载流子分离

英文摘要： Recently, organic solar cells based on D-A copolymers have attracted a lot of interest both in scientific and commercial field. Compared with the inorganic solar cells, organic solar cells are very promising because of the low cost, ease of processing, thin film flexibility, etc. However, the power conversion efficiencies of the organic solar cells are usually low in contrast to the inorganic ones. Therefore, how to enhance the efficiencies of the organic solar cells is the focus of studies in the relative field. Currently, scientists have realized that understanding the photoinduced charge generation dynamics in the bulk heterojunction (BHJ) blends is especially important to improve the light-to-current conversion. Even though it has been studied for several years, there is still no universal consensus about the precise mechanisms. In our project, we will apply few-cycle laser pulse in the ultrafast transient absorption spectroscopy to study the charge generation and recombination processed in the organic solar cells with D-A copolymers as the donor. Since most of the laser spectroscopy in bulk heterojunction are studied by visible laser pulses, the photoinduced mechanism under even shorter wavelength has been rarely studied. At first, we will use ultrashort visible laser pulse with duration of 6 fs to clarify the primary photoexcitations is exciton or free charge carriers. Also, we will study the intramolecular charge transfer character in the PBDTTT copolymers using the laser pulse centered at 400nm with duration of 9 fs for the first time to our knowledge, and investigate the possible influence on the charge separation in the organic solar cells. Furthermore, also for the first time, we investigate the charge photogeneration by excite the donor to its second absorption band using the laser excitation center at 400nm with pulse duration shorter than 10 fs. We will focus our attention on the study on the photoinduced excited-state delocalization and its contribution to the full dissociation of electron and hole. We hope the results achieved in our project could be use for designing new low-bandgap organic semiconductors and to improve energy conversion at photon energies largely exceeding the bandgap.

英文关键词： Ultrafast Laser Spectroscopy;Femtosecond Laser;Organic Solar Cells;Bulk Heterojunction;Charge Separation