Electrodeposited PEDOT:PSS-Al2O3 Improves the Steady-State Efficiency of Inverted Perovskite Solar Cells

Abstract

The atomic layer deposition (ALD) of Al2O3 between perovskite and the hole transporting material (HTM) PEDOT:PSS has previously been shown to improve the efficiency of perovskite solar cells. However, the costs associated with this technique make it unaffordable. In this work, the deposition of an organic–inorganic PEDOT:PSS-Cl-Al2O3 bilayer is performed by a simple electrochemical technique with a final annealing step, and the performance of this material as HTM in inverted perovskite solar cells is studied. It was found that this material (PEDOT:PSS-Al2O3) improves the solar cell performance by the same mechanisms as Al2O3 obtained by ALD: formation of an additional energy barrier, perovskite passivation, and increase in the open-circuit voltage (Voc) due to suppressed recombination. As a result, the incorporation of the electrochemical Al2O3 increased the cell efficiency from 12.1% to 14.3%. Remarkably, this material led to higher steady-state power conversion efficiency, improving a recurring problem in solar cells.

Electrocatalytic Poly(3,4-ethylenedioxythiophene) for Electrochemical Conversion of 5-Hydroxymethylfurfural

“…In particular, a transition from quinoid to benzoid structure, as depicted in Figure 3i, was reported to be linked to a blue shift of the C α �C β symmetric signal. 55 This is consistent with the formation of highly doped poly (3,4-ethylenedioxythiophene) characterized by a larger fraction of bipolaron charge carriers, if compared to the parent material, which may be instrumental in achieving and maintaining a higher current density during the electrolysis. 59 ■ CONCLUSIONS In this study, the good electrocatalytic properties of PEDOT toward the TEMPO/TEMPO(+) redox mediator were documented.…”

“…Typically, PEDOT overoxidation yields the formation of sulfoxide and/or sulfone groups that generate from the oxidation of the thiophene sulfur atoms. 28,54,55 As displayed in Figure S22, the absence of any relevant new feature in the typical range of these oxidized sulfur groups (i.e., 1000−1200 cm −1 ) after electrolysis confirms the chemical stability of PER, PSS, NAF, and AQ. 55−57 In general, the Raman spectra of doped PEDOT films are dominated by a prominent peak at ∼1410−1440 cm −1 , which results from a combination of the two C α �C β symmetric stretching vibrations for the neutral and the oxidized form structures, respectively, the latter located at higher wavenumbers.…”

“…According to the experimental conditions applied in this study, electrochemically promoted overoxidation is the most likely pathway of degradation that could be expected when the PEDOT is constantly biased at anodic potentials. Typically, PEDOT overoxidation yields the formation of sulfoxide and/or sulfone groups that generate from the oxidation of the thiophene sulfur atoms. ,, As displayed in Figure S22, the absence of any relevant new feature in the typical range of these oxidized sulfur groups (i.e., 1000–1200 cm –1 ) after electrolysis confirms the chemical stability of PER, PSS, NAF, and AQ. − In general, the Raman spectra of doped PEDOT films are dominated by a prominent peak at ∼1410–1440 cm –1 , which results from a combination of the two C α C β symmetric stretching vibrations for the neutral and the oxidized form structures, respectively, the latter located at higher wavenumbers . A shift of this main signal to lower wavenumbers has been linked to a reduction of the doping level of the polymer. ,, As detailed in Figure S22a, in the case of PER, a red shift (∼10 cm –1 ) and a narrowing of the main peak can be noticed for the electrochemically stressed film (see also Figure S23).…”

Numerical Evaluation of Novel Bio‐Photovoltaic Devices Inspired by Photosynthetic Process and High Poly (3,4‐Ethylenedioxythiophene): Poly (styrenesulfonate) Efficacy as Hole Transport Layer

“…Because of its broadband transparency, high electrical power of conducting, easy solution processability, high work function, flexibility, variety of techniques available for film formation, and low commercial cost, which make it compatible for use as HTL with many active layer materials such as PSI. [34][35][36][37][38] However, it is still a challenge to fabricate photovoltaic devices using PEDOT:PSS. One of the leading causes is its highly acidic and hygroscopic nature which leads to the corrosion of ITO and decomposition of the absorber layer due to moisture absorption.…”

“…[ 34 ] Another potentially effective strategy has been exhibited by applying an electrodeposited PEDOT: PSS/Al 2 O 3 HTM bilayer, which would give rise to the reduction of charge recombination as the result of the generation of a higher electron energy barrier and the transport of holes by tunneling. [ 35 ] Moreover, the V 2 O 5 incorporated devices (V 2 O 5 ‐PEDOT:PSS (PVO)) in comparison with the PEDOT only devices are a promising HTL candidate due to the formation of electrically barrier‐free cascading contact for the passage of holes across the interface. [ 37 ] The abovementioned approaches have only been studied experimentally for other cell types, and the available literature for PSI solar cells is limited.…”