Effect of ultraviolet absorptivity and waterproofness of poly(3,4-ethylenedioxythiophene) with extremely weak acidity, high conductivity on enhanced stability of perovskite solar cells

The poor long-term stability of perovskite solar cells (PSCs) tremendously hampers their future commercialization though their superior photovoltaic efficiencies. To enhance the device stability, a new poly(3,4-ethylenedioxythiophene):sulfonated acetone-formaldehyde (PEDOT:SAF) with higher PEDOT content (2:1) is developed considering the excellent dispersing capacity of SAF. PEDOT:SAF exhibits extremely lower acidity with pH value of 6 and higher conductivity of 3.12 S/cm comparing with the former reported sample with lower PEDOT content. Moreover, PEDOT:SAF film shows superior ultraviolet (UV) absorptivity originated from the fluorescence effect of SAF and unexceptionable film waterproofness on account of the high PEDOT content. As a result, the PSC incorporating PEDOT:SAF as the hole extraction layer (HEL) achieves higher power conversion efficiency (PCE) and highly enhanced device stability than the traditional PEDOT:PSS-based device. After 28 days of storage time, our device retains 83.2% from its original PCE, while almost half-degradation is experienced in the PEDOT:PSS controlled device. In addition, SAF is renewable with more simple and inexpensive preparation than that of PSS. Undoubtedly, this new PEDOT:SAF provides us a scaffold for designing stable PSC, and this platform is also shared in other photovoltaic technologies. (C) 2017 Elsevier B.V. All rights reserved.