Roles of Acceptor Guests in Tuning the Organic Solar Cell Property Based on an Efficient Binary Material System with a Nearly Zero Hole-Transfer Driving ForceShow others and affiliations
2020 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 32, no 12, p. 5182-5191Article in journal (Refereed) Published
Abstract [en]
Sub-picosecond hole transfer has been recently observed in several narrow band gap nonfullerene small-molecule acceptor (NFA)-based binary blended organic solar cell (OSC) systems operating with negligible energetic driving forces. As the driving forces are near zero, how the added acceptor/donor guests tune the barrier-free hole-transfer dynamics of these systems remains very unclear. In this study, we report a new NFA (BTCT-2Cl) that conducts a sub-picosecond hole transfer (2 ps) for efficient photocurrent generation when pairing with PM6 though the energetic offset is only 0.02 eV. We observe that the added nonfullerene and PCBM components differently tune the charge generation and recombination when selectively exciting BTCT-2Cl. After adding PC71BM, the hole transfer from the host BTCT-2Cl to the host donor is greatly accelerated, with the rate significantly reduced to 0.29 ps and the charge generation becomes more efficient; on the contrary, recombination is prolonged and a larger fill factor is obtained after adding an NFA guest, here, IT-4F. The different tuning on the host binary hole-transfer dynamics is likely related with the phase crystallinity and the domain size changed after adding different acceptor guests. Over 16% efficiency is obtained on the PC71BM-based ternary device that outperforms the host binary and the IT-4F-based ternary solar cells (both showing over 15% efficiencies). The results clearly demonstrate that adding PCBM or NFA guests enables a very effective and different tuning on the hole-transfer rates and the recombination rates between the barrier-free host binary components, hence leading to efficient tuning on the short-circuit current density and fill factor, which outlines new strategies toward designing high-efficiency ternary blended OSC systems.
Place, publisher, year, edition, pages
AMER CHEMICAL SOC , 2020. Vol. 32, no 12, p. 5182-5191
National Category
Condensed Matter Physics
Identifiers
URN: urn:nbn:se:liu:diva-167660DOI: 10.1021/acs.chemmater.0c01245ISI: 000543738500030OAI: oai:DiVA.org:liu-167660DiVA, id: diva2:1454743
Note
Funding Agencies|National Natural Science Foundation of China (NSFC)National Natural Science Foundation of China [91433202, 21773262, 21327805]; Inner Mongolia Normal University; Taishan Scholars Program of Shandong Province [tsqn201812101]; Natural Science Foundation of Hebei ProvinceNatural Science Foundation of Hebei Province [B2016201014]; NSFC/RGC Joint Research SchemeNational Natural Science Foundation of China [N_CUHK418/17]; Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation [2016.0059]; Swedish Government Research Area in Materials Science on Functional Materials at Linkoping University [SFO-Mat-LiU 200900971]; China Scholarship Council (CSC)China Scholarship Council [201708370115]
2020-07-202020-07-202020-07-20