Design of Super-Paramagnetic Core鈥揝hell Nanoparticles for Enhanced Performance of Inverted Polymer Solar Cells

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• 作者：Johny Jaramillo ; Bryan W. Boudouris ; C茅sar A. Barrero ; Franklin Jaramillo
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：November 18, 2015
• 年：2015
• 卷：7
• 期：45
• 页码：25061-25068
• 全文大小：452K
• ISSN：1944-8252

文摘

Controlling the nature and transfer of excited states in organic photovoltaic (OPV) devices is of critical concern due to the fact that exciton transport and separation can dictate the final performance of the system. One effective method to accomplish improved charge separation in organic electronic materials is to control the spin state of the photogenerated charge-carrying species. To this end, nanoparticles with unique iron oxide (Fe₃O₄) cores and zinc oxide (ZnO) shells were synthesized in a controlled manner. Then, the structural and magnetic properties of these core鈥搒hell nanoparticles (Fe₃O₄@ZnO) were tuned to ensure superior performance when they were incorporated into the active layers of OPV devices. Specifically, small loadings of the core鈥搒hell nanoparticles were blended with the previously well-characterized OPV active layer of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM). Upon addition of the core鈥搒hell nanoparticles, the performance of the OPV devices was increased up to 25% relative to P3HT-PCBM active layer devices that contained no nanoparticles; this increase was a direct result of an increase in the short-circuit current densities of the devices. Furthermore, it was demonstrated that the increase in photocurrent was not due to enhanced absorption of the active layer due to the presence of the Fe₃O₄@ZnO core鈥搒hell nanoparticles. In fact, this increase in device performance occurred because of the presence of the superparamagnetic Fe₃O₄ in the core of the nanoparticles as incorporation of ZnO only nanoparticles did not alter the device performance. Importantly, however, the ZnO shell of the nanoparticles mitigated the negative optical effect of Fe₃O₄, which have been observed previously. This allowed the core鈥搒hell nanoparticles to outperform bare Fe₃O₄ nanoparticles when the single-layer nanoparticles were incorporated into the active layer of OPV devices. As such, the new materials described here present a tangible pathway toward the development of enhanced design schemes for inorganic nanoparticles such that magnetic and energy control pathways can be tailored for flexible electronic applications.