Indium‐Free Perovskite Solar Cells Enabled by Impermeable Tin‐Oxide Electron Extraction Layers

Abstract

Corrosive precursors used for the preparation of organic-inorganic hybrid perovskite photoactive layers prevent the application of ultrathin metal layers as semitransparent bottom electrodes in perovskite solar cells (PVSCs). This study introduces tin-oxide (SnO ) grown by atomic layer deposition (ALD), whose outstanding permeation barrier properties enable the design of an indium-tin-oxide (ITO)-free semitransparent bottom electrode (SnO /Ag or Cu/SnO ), in which the metal is efficiently protected against corrosion. Simultaneously, SnO functions as an electron extraction layer. We unravel the spontaneous formation of a PbI interfacial layer between SnO and the CH NH PbI perovskite. An interface dipole between SnO and this PbI layer is found, which depends on the oxidant (water, ozone, or oxygen plasma) used for the ALD growth of SnO . An electron extraction barrier between perovskite and PbI is identified, which is the lowest in devices based on SnO grown with ozone. The resulting PVSCs are hysteresis-free with a stable power conversion efficiency (PCE) of 15.3% and a remarkably high open circuit voltage of 1.17 V. The ITO-free analogues still achieve a high PCE of 11%.

Perovskite Solar Cells: From the Laboratory to the Assembly Line

“…A few studies have reported creative ways to circumvent the use of FTO/ITO electrodes. For instance, the use of SnO x layers in combination with ultrathin silver electrodes of about 6 nm was reported in a PSC (Figure A). The authors made use of conformal layers grown by atomic layer deposition (ALD), which is capable to depositing monolayers of different materials.…”

Improving the performance of inverted organic solar cells by embedding silica‐coated silver nanoparticles deposited by electron‐beam evaporation

“…It could also be assumed that the presence of the ultrathin silica layer that is a metal oxide used as an interlayer in inverted OSCs can improve electron extraction. Several studies have reported that the use of a metal oxide layer as interlayer between the organic layer and the anode/cathode facilitates charge extraction and affords well behaved highly efficient third generation solar cells . In addition, the silica layer might be regarded as a dielectric barrier layer around the MNPs incorporated in the OSCs.…”

“…Several studies have reported that the use of a metal oxide layer as interlayer between the organic layer and the anode/cathode facilitates charge extraction and affords well behaved highly efficient third generation solar cells. [35][36][37][38][39][40] In addition, the silica layer might be regarded as a dielectric barrier layer around the MNPs incorporated in the OSCs.…”

All‐Oxide MoOx/SnOx Charge Recombination Interconnects for Inverted Organic Tandem Solar Cells

“…[11] For SnO x grown by ALD at low temperature, ultraviolet photoelectron spectroscopy (UPS) and inverse photoemission spectroscopy (IPES) data provided a band gap of 3.72eV. [48] Taking the latter value as the band-gap in our line-up (Figure 3c) would even result in a CB offset between MoO x and SnO x close to zero. From the distance of the Fermi level and the CB edge (E CB − E F ), we can derive a complementary estimate of the carrier density in our SnO x .…”

“…[18] Recently, SnO x has also been considered as EEL for solar cells based on hybrid perovskites with improved efficiency and long-term stability. [47][48][49][50] Initially, we have prepared single junction reference devices with a thickness of the photoactive layers identical to that of the sub-cells in the tandem devices. The optimum thickness of the active layers for current matching has been determined by an optical simulation taking into account the absorption characteristics of the photoactive layers in the tandem cell and the external quantum efficiency (EQE) of the single junction devices ( Figure S1, Supporting Information).…”