Title: Dimethylammonium Addition to Halide Perovskite Precursor Increases Vertical and Lateral Heterogeneity

Abstract

Adding a large A-site cation, such as dimethylammonium (DMA), to the perovskite growth solution has been shown to improve the performance and long-term operational stability of halide perovskite solar cells. To better understand the origins of these improvements, we explore the changes in film structure, composition, and optical properties of a formamidinium (FA), Cs, Pb, and mixed halide perovskite following the addition of DMA to the perovskite growth solution in the ratio of DMA_0.1FA_0.6Cs_0.3Pb(I_0.8Br_0.2)₃. Using time-of-flight secondary-ion mass spectrometry (TOF-SIMS), we show that DMA is indeed incorporated into the perovskite, with a higher DMA concentration at the surface. Using a combination of photoluminescence (PL) microscopy and photoinduced force microscopy-based (PiFM) nanoinfrared (nanoIR), we demonstrate that incorporating DMA into the film leads to increased local heterogeneity in the local bandgap and clustering of the local formamidinium (CH₅N₂⁺) composition. In addition, using nano-X-ray diffraction, we demonstrate that DMA incorporation also alters the local structural composition by changing the local d-spacing distribution and grain size. Our results suggest that compositional variations in the organic cations at the A-site drive the structural heterogeneity observed in the case of DMA-incorporated films. Our results also suggest that while current DMA-additive-based approaches do have benefits to operationalmore » stability and device performance, process optimization to achieve local compositional and structural homogeneity could further boost both of these gains in performance, bringing further gains to solar cells using DMA additives.« less

Authors:

Jariwala, Sarthak  ^[1];

• Search DOE PAGES for author "Jariwala, Sarthak"
• Search DOE PAGES for ORCID "0000-0002-7020-9008"

Kumar, Rishi E. ^[2]; Eperon, Giles E.  ^[3];

• Search DOE PAGES for author "Eperon, Giles E."
• Search DOE PAGES for ORCID "0000-0001-9600-4847"

Shi, Yangwei ^[1]; Fenning, David P.  ^[2];

• Search DOE PAGES for author "Fenning, David P."
• Search DOE PAGES for ORCID "0000-0002-4609-9312"

Ginger, David S.  ^[1]

• Search DOE PAGES for author "Ginger, David S."
• Search DOE PAGES for ORCID "0000-0002-9759-5447"

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+ Show Author Affiliations

1. Univ. of Washington, Seattle, WA (United States)
2. Univ. of California, San Diego, CA (United States)
3. National Renewable Energy Lab. (NREL), Golden, CO (United States); Swift Solar Inc., San Carlos, CA (United States)

Publication Date:

Mon Dec 13 00:00:00 EST 2021

Research Org.:

National Renewable Energy Lab. (NREL), Golden, CO (United States); Univ. of Washington, Seattle, WA (United States); Georgia Institute of Technology, Atlanta, GA (United States); Univ. of Colorado, Boulder, CO (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office; National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1841362

Alternate Identifier(s):

OSTI ID: 1910154

Report Number(s):

NREL/JA-5900-81917
Journal ID: ISSN 2380-8195; MainId:82690;UUID:1e14934b-b953-40ad-ae79-79b62500e464;MainAdminID:63676

Grant/Contract Number:  

AC36-08GO28308; EE0008747; NNCI-1542101

Resource Type:

Accepted Manuscript

Journal Name:

ACS Energy Letters

Additional Journal Information:

Journal Volume: 7; Journal Issue: 1; Journal ID: ISSN 2380-8195

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; additives; lead compounds; optical properties; optimization; perovskite solar cells; positive ions; secondary ion mass spectrometry; perovskite solar cell; lateral heterogeneity; additive