Poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) Modified by Water for Efficient Inverted Perovskite Solar Cells

Abstract

Poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) is a popular hole transport material in inverted perovskite solar cells (PSCs). However, it is required to modify the PEDOT:PSS to achieve high-performance PSCs. Herein, a facile method to modify PEDOT:PSS using water to improve the performance of inverted PSCs is developed. The modification impact on the physical properties of the PEDOT:PSS films is systemically studied. The results show that the transmittance and resistance of the PEDOT:PSS layer are greatly improved by modification using water without changing its work function. The growth of perovskite films on PEDOT:PSS is also influenced by the modification of PEDOT:PSS using water. Better crystallinity and larger grain sizes of the perovskite film are also achieved, leading to recombination loss being greatly reduced and the performance of the devices significantly improved. The PSCs based on modified PEDOT:PSS exhibit a higher power conversion efficiency (PCE) of 17.28 % and higher open-circuit voltage (V oc ) of 1.06 V compared to control devices prepared with unmodified PEDOT:PSS (PCE ¼ 12.49%, V oc ¼ 0.99 V). This work provides a facile method to modify PEDOT:PSS to prepare high-performance inverted PSCs.

Impact of Substrate Hydrophobicity on Layer Composition and Work Function of PEDOT:PSS Thin Films

“…The layer thickness is controlled by the PH1000-to-H 2 O ratio of the solution and by the spinning speed (Table S1, Supporting Information), and varying these parameters to prepare further PEDOT:PSS samples on wet-cleaned ITO does not impact the work function (Figure 2b). For applications, ITO is frequently cleaned by UV-ozone [8,30] and also such treatment does not affect the work function of PEDOT:PSS thin films (Figure 2c).…”

“…Electrode work functions are decisive for interfacial energy-level alignment and for the performance of hybrid (opto-)electronic devices. [1][2][3][4] The conductive polymer poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is frequently used as a hole-injecting electrode in devices such as light-emitting diodes, [5][6][7] photovoltaic devices, [2,[8][9][10] and field-effect transistors. [11,12] The basis of these widespread applications of PEDOT:PSS thin films is their high and tunable work function which ranges-depending on the PEDOT:PSS formulation, substrates, processing conditions, etc.-from 4.7 to 6.1 eV.…”