Improving the efficiency of CH3NH3PbI3 based photovoltaics by tuning the work function of the PEDOT:PSS hole transport layer. (December 2015)

• Record Type: Journal Article
• Authors: Chang, Sheng Hsiung; Lin, Kuen-Feng; Chiu, Kuo Yuan; Tsai, Chia-Lung; Cheng, Hsin-Ming; Yeh, Shih-Chieh; Wu, Wen-Ti; Chen, Wei-Nien; Chen, Chin-Ti; Chen, Sheng-Hui; Wu, Chun-Guey
• Is Part Of: Solar energy. Volume 122(2015)
• Page Start: 892
• Page End: 899
• Publication Date: 2015-12
• Subjects: PEDOT:PSS -- Organometal halide perovskite -- Photovoltaics; Solar energy -- Periodicals; Solar engines -- Periodicals; 621.47
• DOI: 10.1016/j.solener.2015.10.018
• Languages: English
• ISSNs: 0038-092X

Abstract

Highlights: The PCE was improved from 5.6% to 11.7% by tuning the work function of HTL. The Fermi levels of HTLs were determined by square-wave voltammetry method. The work functions of HTLs were measured by a photoelectron spectrometer. The work function of HTL increases with an increase in the carrier density of PEDOT. The increased carrier density is due to the conformational changes in the PEDOT chains. Abstract: The open-circuit voltage of CH3 NH3 PbI3 based photovoltaics was enhanced from 0.77 V to 0.9 V, which resulted in an improvement of the average power conversion efficiency from 5.63% to 11.74% achieved by tuning the work function of the poly(3, 4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hole transport layer. The higher work function of the PEDOT:PSS (1:20 wt%) thin film, as compared to the PEDOT:PSS (1:6 wt%) and PEDOT:PSS (1:2.5 wt%) thin films, was observed using photoelectron spectrometer. The carrier density of PEDOT was obtained by analyzing the transmittance spectrum of PEDOT:PSS/glass with the transfer matrix method. The Drude model can be used to explain the increased work function of the PEDOT:PSS thin film obtained by decreasing the ratio of PEDOT to PSS. The increased carrier density of the PEDOT in PEDOT:PSS thin films originated from conformational changes in the PEDOT chains as confirmed by Raman scattering spectroscopy.