Large scale two-dimensional nanobowl array high efficiency polymer solar cell

Abstract

A two-dimensional nanobowl array (2D-NBRs) with a unique honeycomb nanostructure was demonstrated with controllable morphologies synthesized by the Langmuir–Blodgett (LB) method. The periodicity of 2D-NBRs can be controlled by utilizing different diameters of polystyrene (PS) balls ranged from 500 nm, 870 nm, 1 μm to 2 μm. The reflectance measurements revealed that the planar structure with a poly(3-hexylthiophene) (P3HT)/(6,6)-phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunction layer as an active layer exhibits a reflectance of ∼20 %, while a significant reduction of the reflectance <5–7 % can be achieved after formation of 2D-NBRs at a PS ball diameter of 500 nm, which perfectly matches simulation results. From experimental results, the highest efficiency of 5.4 % with a filling factor of 66 % was achieved for the device with 2D-NBRs at PS ball diameter of 870 nm. Compared to a planar device with an efficiency of 3.9 %, a maximum enhancement of ∼40 % can be achieved owing to the enhancement of Jsc because of unique honeycomb geometry, which exhibits a broadband and omnidirectional light harvesting behavior. Furthermore, a flexible solar cell was demonstrated with an enhanced efficiency of 30 % for a planar structure of 1 % to 1.3 % for 2D-NBRs structure.