title: Polymer bulk heterojunction solar cells with PEDOT:PSS bilayer structure as hole extraction layer.
abstract: A high current density obtained in a limited, nanometer-thick region is important for high efficiency polymer solar cells (PSCs). The conversion of incident photons to charge carriers only occurs in confined active layers; therefore, charge-carrier extraction from the active layer within the device by using solar light has an important impact on the current density and the related to power conversion efficiency. In this study, we observed a surprising result, that is, extracting the charge carrier generated in the active layer of a PSC device, with a thickness-controlled PEDOT:PSS bilayer that acted as a hole extraction layer (HEL), yielded a dramatically improved power conversion efficiency in two different model systems (P3HT:PC₆₀BM and PCDTBT:PC₇₀BM). To understand this phenomenon, we conducted optical strength simulation, photocurrent-voltage measurements, incident photon to charge carrier efficiency measurements, ultraviolet photoelectron spectroscopy, and AFM studies. The results revealed that approximately 60 nm was the optimum PEDOT:PSS bilayer HEL thickness in PSCs for producing the maximum power conversion efficiency.
authors: School of Chemical Engineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea.
authors: Wanjung
authors: W
authors: Kim
authors: Namhun
authors: N
authors: Kim
authors: Jung Kyu
authors: JK
authors: Kim
authors: Insun
authors: I
authors: Park
authors: Yeong Suk
authors: YS
authors: Choi
authors: Dong Hwan
authors: DH
authors: Wang
authors: Heeyeop
authors: H
authors: Chae
authors: Jong Hyeok
authors: JH
authors: Park
mesh_terms: D004553:Electric Conductivity; D011211:Electric Power Supplies; D011137:Polystyrenes / Q000737:chemistry*; D012993:Solar Energy; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D011137:Polystyrenes; D013876:Thiophenes; C533756:poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)