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.
Highlights
The solution processing of organic–inorganic perovskite solar cells is a promising route for the fabrication of cost-effective photovoltaic devices [1,2]
This study presented the fabrication and evaluation of inverted perovskite solar cells, using as hole transporting material (HTM) a PEDOT-Al2O3 bilayer obtained by electrochemical methods
The efficiency of the solar cell increased from 12.1% to 14.3%
Summary
The solution processing of organic–inorganic perovskite solar cells is a promising route for the fabrication of cost-effective photovoltaic devices [1,2]. Unlike direct solar cells, inverted architecture features devices with the HTM being deposited over the conductive oxide, this material must be transparent to allow incident light to reach the active layer [3,4]. PEDOT:PSS is a conductive polymer widely used as HTM in inverted perovskite solar cells due to its high transparency, flexibility, and low commercial cost. The same authors reported that an ALD Al2O3 interlayer between the perovskite film and the HTM Spiro-OMeTAD improved both the dynamic and steady-state PCE of the cells, increasing from 15% to 18% [17]. We present similar improvements to those achieved by ALD in inverted PEDOT:PSS devices, but using an electrodeposited PEDOT:PSS/Al2O3 HTM bilayer. The bilayer was found to generate an effective energy barrier and confer protection to the polymer from halides, maintaining its semiconducting state
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