Performance enhancement in organic photovoltaics with metal or carbon based nanomaterials

Abstract

Organic photovoltaics (OPVs) are renewable energy conversion devices with distinct potential advantages, such as solution processibility, mechanical flexibility and light-weight. Despite promising progress in device performance, power conversion efficiency (PCE) has to be enhanced for the mass production and commercialization. One straightforward way for the performance enhancement in OPVs is the incorporation of nanomaterials. In this study, I have employed two kinds of nanomaterials into OPVs to enhance the performance of devices. Firstly, nanostructured materials of plasmonic nanoparticles have been introduced to OPVs with expectations for plasmonic effects. By developing triangular-shaped clusters of plasmonic nanoparticles, it can result in strong enhancement of electromagnetic fields induced by near-field plasmonic coupling effects. Direct incorporation of gold nanoparticle clusters (Au NPCs) or Au NPC/graphene oxide nanocomposites (Au NPC-GOs) at the bottom of organic active layer improved the PCE over 10 %. The solution processibility of metal NP assemblies is compatible to conventional low-cost OPV process. Moreover, this approach can be further exploited by tuning the shape, dimension and chemical composition of assemblies, the size of constituting NPs, and the interparticle gaps. Furthermore, I have synthesized carbon nanotube (CNT)/polymer nanocomposites to be employed in OPVs as an additive for enhancing charge transport in the organic active layer. To improve the dispersibility of CNTs in the organic active layer, N-doped CNTs wrapped with end-functionalized conductive polymer (P3CPT) were synthesized by simple mixing in the organic solvent. By incorporating N-CNT/P3CPT nanocomposites into the organic active layer, short-circuit current of OPV was enhanced remarkably owing to superior electrical properties of CNTs. We anticipate that this novel concept of employing nanostructured materials can be potentially useful for various organic optoelectronic devices with good processibility and high efficiency.