Side-Chain Engineering of Diketopyrrolopyrrole-Based Hole-Transport Materials to Realize High-Efficiency Perovskite Solar Cells
- Authors
- Sharma, Amit; Singh, Ranbir; Kini, Gururaj P.; Kim, Ji Hyeon; Parashar, Mritunjaya; Kim, Min; Kumar, Manish; Kim, Jong Seung; Lee, Jae-Joon
- Issue Date
- 17-2월-2021
- Publisher
- AMER CHEMICAL SOC
- Keywords
- perovskite solar cell; donor-acceptor small molecules; hole-transport materials; morphology; diketopyrrolopyrrole; side-chain engineering; device stability
- Citation
- ACS APPLIED MATERIALS & INTERFACES, v.13, no.6, pp.7405 - 7415
- Indexed
- SCIE
SCOPUS
- Journal Title
- ACS APPLIED MATERIALS & INTERFACES
- Volume
- 13
- Number
- 6
- Start Page
- 7405
- End Page
- 7415
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/49563
- DOI
- 10.1021/acsami.0c17583
- ISSN
- 1944-8244
- Abstract
- The design and synthesis of a stable and efficient hole-transport material (HTM) for perovskite solar cells (PSCs) are one of the most demanding research areas. At present, 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (spiro-MeOTAD) is a commonly used HTM in the fabrication of high-efficiency PSCs; however, its complicated synthesis, addition of a dopant in order to realize the best efficiency, and high cost are major challenges for the further development of PSCs. Herein, various diketopyrrolopyrrole-based small molecules were synthesized with the same backbone but distinct alkyl side-chain substituents (i.e., 2-ethylhexyl-, n-hexyl-, ((methoxyethoxy)ethoxy)ethyl-, and (2-((2-methoxyethoxy)ethoxy)ethyl)acetamide, designated as D-1, D-2, D-3, and D-4, respectively) as HTMs. The variation in the alkyl chain has shown obvious effects on the optical and electrochemical properties as well as on the molecular packing and film-forming ability. Consequently, the power conversion efficiency (PCE) of the PSC under one sun illumination (100 mW cm(-2)) is shown to increase in the order of D-1 (8.32%) < D-2 (11.12%) < D-3 (12.05%) < D-4 (17.64%). Various characterization techniques reveal that the superior performance of D-4 can be ascribed to the well-aligned highest occupied molecular orbital energy level with the counter electrode, the more compact p-p stacking with a higher coherence length, and the excellent hole mobility of 1.09 x 10(-3) cm(2) V-1 s(-1), thus providing excellent energetics for effective charge transport with minimal charge-carrier recombination. Furthermore, the addition of the dopant Li-TFSI in D-4 is shown to deliver a remarkable PCE of 20.19%, along with a short-circuit current density (J(SC)), open-circuit voltage (V-OC), and fill factor (FF) of 22.94 mA cm(-2), 1.14 V, and 73.87%, respectively, and superior stability compared to that of other HTMs. These results demonstrate the effectiveness of side-chain engineering for tailoring the properties of HTMs, thus offering new design tactics to fabricate for the synthesis of highly efficient and stable HTMs for PSCs.
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