A universal Ti₃C₂ assisted strategy facilitates hole extraction of PEDOT:PSS anode interface layer for over 19% efficiency organic photovoltaics

Abstract

Low hole extraction efficiency is a key factor restricting the performance of organic photovoltaics (OPVs). Improving the conductivity of PEDOT:PSS [poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)] and reducing its large extraction barrier with the active layer is viewed as an important direction to increase the hole extraction efficiency of OPVs. In this work, few-layer two-dimensional titanium carbide (Ti₃C₂) nanosheets were prepared by HCl/LiF etching and doped into PEDOT:PSS to fabricate OPV devices. Ti₃C₂ nanosheets induced the configuration transformation of PEDOT from spiral benzoyl to linear quinone structure, form tightly packed large-size PEDOT nanocites, and connect these conductive nanocites to construct a new charge transport channel, thus boosting the conductivity of the PEDOT:PSS anode interface layer. In addition, Ti₃C₂ nanosheets adjusted the work function of PEDOT:PSS, thus decreasing the hole extraction barrier in OPVs. As 2% volume of Ti₃C₂ doping into PEDOT:PSS interlayer, the maximum power conversion efficiency of PTzBI-oF:PYF-T-o, D18:L8-BO, and PM6:L8-BO-based OPVs boosted from 15.61%, 17.92% and 15.49% to 16.83%, 19.05% and 17.33%, respectively. Our work can provide guidance for facilitating hole extraction of PEDOT:PSS, which is expected to contribute to the further progress of OPVs.

Keywords

Titanium carbide / organic photovoltaic / anode interface layer / conductivity / hole extraction

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