Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 6: Organic Molecules on Inorganic Substrates I: Electronic, Optical and other Properties
O 6.10: Talk
Monday, March 16, 2020, 13:00–13:15, REC C 213
Direct observation of conductive polymer induced inversion layer in n-Si and correlation to solar cell performance — •rongbin wang1,2, yusheng wang2, chen wu2, tianshu zhai2, jiacheng yang2, baoquan sun2, steffen duhm2, and norbert koch1,2 — 1Institut für Physik, Humboldt-Universität zu Berlin, Germany — 2Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, China
Heterojunctions formed by PEDOT:PSS films and n-type silicon were investigated by photoelectron spectroscopy. By diluting the original PEDOT:PSS solution and increasing the spin-coating speed, a series of PEDOT:PSS thin films with nominal thicknesses down to 5 nm were achieved on n-Si substrates. Large shifts of Si 2p core levels upon PEDOT:PSS deposition provide direct evidence that a dopant-free p-n junction, i.e., an inversion layer, is formed within Si. Among the investigated PEDOT:PSS formulations, the largest induced band bending within Si (0.71 eV) is found for PH1000 combined with a wetting agent and the solvent additive dimethyl sulfoxide (DMSO). Without DMSO, the induced band bending is reduced, as is also the case with a PEDOT:PSS (AI4083) formulation with higher PSS content. By comparing PEDOT:PSS/n-Si solar cells with MoOx/n-Si cells, it becomes apparent that a large contact-induced band bending does not necessarily lead to a high Voc. Adequate passivation of the silicon surface to decrease recombination and high conductivity of the covering layer are also needed to achieve high PCE devices. Reference: Wang et al., Adv. Funct. Mater. 2019, 1903440 (doi.org/10.1002/adfm.201903440)