Dataset Information

SnO _x Atomic Layer Deposition on Bare Perovskite-An Investigation of Initial Growth Dynamics, Interface Chemistry, and Solar Cell Performance.

ABSTRACT: High-end organic-inorganic lead halide perovskite semitransparent p-i-n solar cells for tandem applications use a phenyl-C₆₁-butyric acid methyl ester (PCBM)/atomic layer deposition (ALD)-SnO _x electron transport layer stack. Omitting the PCBM would be preferred for manufacturing, but has in previous studies on (FA,MA)Pb(Br,I)₃ and (Cs,FA)Pb(Br,I)₃ and in this study on Cs_0.05FA_0.79MA_0.16PbBr_0.51I_2.49 (perovskite) led to poor solar cell performance because of a bias-dependent light-generated current. A direct ALD-SnO _x exposure was therefore suggested to form a nonideal perovskite/SnO _x interface that acts as a transport barrier for the light-generated current. To further investigate the interface formation during the initial ALD SnO _x growth on the perovskite, the mass dynamics of monitor crystals coated by partial p-i-n solar cell stacks were recorded in situ prior to and during the ALD using a quartz crystal microbalance. Two major finds were made. A mass loss was observed prior to ALD for growth temperatures above 60 °C, suggesting the decomposition of the perovskite. In addition, a mostly irreversible mass gain was observed during the first exposure to the Sn precursor tetrakis(dimethylamino)tin(IV) that is independent of growth temperature and that disrupts the mass gain of the following 20-50 ALD cycles. The chemical environments of the buried interface were analyzed by soft and hard X-ray photoelectron spectroscopy for a sample with 50 ALD cycles of SnO _x on the perovskite. Although measurements on the perovskite bulk below and the SnO _x film above did not show chemical changes, additional chemical states for Pb, Br, and N as well as a decrease in the amount of I were observed in the interfacial region. From the analysis, these states and not the heating of the perovskite were concluded to be the cause of the barrier. This strongly suggests that the detrimental effects can be avoided by controlling the interfacial design.

SUBMITTER: Hultqvist A

PROVIDER: S-EPMC7885702 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature

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SnO x Atomic Layer Deposition on Bare Perovskite-An Investigation of Initial Growth Dynamics, Interface Chemistry, and Solar Cell Performance.

Hultqvist Adam A Jacobsson T Jesper TJ Svanström Sebastian S Edoff Marika M Cappel Ute B UB Rensmo Håkan H Johansson Erik M J EMJ Boschloo Gerrit G Törndahl Tobias T

ACS applied energy materials 20210104 1

High-end organic-inorganic lead halide perovskite semitransparent p-i-n solar cells for tandem applications use a phenyl-C61-butyric acid methyl ester (PCBM)/atomic layer deposition (ALD)-SnO x electron transport layer stack. Omitting the PCBM would be preferred for manufacturing, but has in previous studies on (FA,MA)Pb(Br,I)3 and (Cs,FA)Pb(Br,I)3 and in this study on Cs0.05FA0.79MA0.16PbBr0.51I2 ...[more]

PMID: 33615157

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Project description:Perovskite photovoltaics has achieved conversion efficiencies of 26.0% by optimizing the optoelectronic properties of the absorber and its interfaces with charge transport layers (CTLs). However, commonly adopted organic CTLs can lead to parasitic absorption and device instability. Therefore, metal oxides like atomic layer-deposited (ALD) SnO2 in combination with fullerene-based electron transport layers have been introduced to enhance mechanical and thermal stability. Instead, when ALD SnO2 is directly processed on the absorber, i.e., without the fullerene layer, chemical modifications of the inorganic fraction of the perovskite occur, compromising the device performance. This study focuses on the organic fraction, particularly the formamidinium cation (FA+), in a CsFAPb(I,Br)3 perovskite. By employing in situ infrared spectroscopy, we investigate the impact of ALD processing on the perovskite, such as vacuum level, temperature, and exposure to half and full ALD cycles using tetrakis(dimethylamido)-Sn(IV) (TDMA-Sn) and H2O. We observe that exposing the absorber to vacuum conditions or water half-cycles has a negligible effect on the chemistry of the perovskite. However, prolonged exposure at 100 °C for 90 min results in a loss of 0.7% of the total formamidinium-related vibrational features compared to the pristine perovskite. Supported by density functional theory calculations, we speculate that FA+ deprotonates and that formamidine desorbs from the perovskite surface. Furthermore, the interaction between TDMA-Sn and FA+ induces more decomposition of the perovskite surface compared to vacuum, temperature, or H2O exposure. During the exposure to 10 ALD half-cycles of TDMA-Sn, 4% of the total FA+-related infrared features are lost compared to the pristine perovskite. Additionally, IR spectroscopy suggests the formation and trapping of sym-triazine, i.e., a decomposition product of FA+. These studies enable to decouple the effects occurring during direct ALD processing on the perovskite and highlight the crucial role of the Sn precursor in affecting the perovskite surface chemistry and compromising the device performance.

Dataset Information

SnO _x Atomic Layer Deposition on Bare Perovskite-An Investigation of Initial Growth Dynamics, Interface Chemistry, and Solar Cell Performance.

Publications

SnO <sub><i>x</i></sub> Atomic Layer Deposition on Bare Perovskite-An Investigation of Initial Growth Dynamics, Interface Chemistry, and Solar Cell Performance.

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