Enhanced Performance and Stability of Ternary Organic Solar Cells Utilizing Two Similar Structure Blend Fullerene‐Free Molecules as Electron Acceptor

Abstract

length region (the absorption peaks are located at 240 and 380 nm for [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and PC 71 BM, respectively) and the deep lowest unoccupied molecular orbital (LUMO) energy levels (the LUMO energy levels are 4.1 eV and 3.9 eV for PCBM and PC 71 BM, respectively). [6,7] Fullerene-free acceptors have recently been vigorously developed and replaced the common fullerene derivative small molecule acceptor materials for high-performance OSCs, which play an important role in the broaden and redshifted absorption widows, and adjusting the LUMO and highest occupied molecular orbital (HOMO) energy levels. [8,9] However, a significant challenge of developed fullerene-free acceptors must be overcome in order to the absorption spectrum of fullerene free is match AM 1.5 G solar simulator and smooth energy levels at the donor/acceptor interface. Recently, the power conversion efficiencies (PCEs) of binary OSCs based on fullerenefree small molecular as acceptors (NFAs) have greatly developed. The single junction OSCs with Y6 as acceptor have led to PCE achieve 15.7% by Zou and co-workers reported. [10] The Peng et al. have reported the recorded PCE of single junction OSCs with Y6 as acceptor and achieved 16.35%. [11] The Erjun group has synthesized the new polymer PE2 and PE63 as donor and Y6 as acceptor and achieved the better photovoltaic performance. [12,13] At the same time, due to the LUMO and HOMO of third component materials located at the medium between donor and acceptor, it is evitable to introduce charge traps at the three kind materials interface. Thus, the third component materials should avoid to form deep charge traps, in addition to the large energy levels offset between HOMO of donor and LUMO of acceptor and complementary absorption peaks of photoactive layer materials. [14][15][16] Meta-alkyl-phenyl-containing 3,9-bis(2-methylene-(3-(1,1dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexyl phenyl)dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′] dithiophene (ITIC) small molecular acceptor (m-ITIC) and alkylthienyl-containing ITIC small molecular acceptor (ITIC-Th) were reported. [17,18] The ITIC-Th exhibit the similar LUMO energy level (E LUMO , 3.85 eV) and significant downshifts of HOMO energy level (E HOMO , 5.66 eV) relative to m-ITIC (the E LUMO and E HOMO of 3.82 and 5.52 eV). Stimulatingly, the remarkable blueshifts absorption peaks for J61 polymer as donor and the blend of m-3,9-bis(2-methylene-(3-(1,1dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexyl phenyl)-dithieno[2,3d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′] dithiophene (ITIC) and ITIC-Th as electron acceptor. The blend of m-ITIC and ITIC-Th as electron acceptor due to the similar lowest unoccupied molecular orbital energy levels and good compatibility among J61, m-ITIC, and ITIC-Th, are beneficial for the small energy barrier at the m-ITIC:ITIC-Th interface. Simultaneously, the ternary photoactive layer can maintain the optimize film morphology and beneficial to ensure effective suppression of charge recombin...

Ternary Blend Organic Solar Cells: Understanding the Morphology from Recent Progress

“…The application of two NFAs in the ternary blend has also shown great potentials in improving the stability. [17,65,84,89,[213][214][215][216][217] Baran et al demonstrated the NFA-based binary and ternary blends could improve the storage lifetime and photostability in comparison to the low-bandgap polymer: fullerene solar cells. [65] In addition, they found that the introduction of O-IDTBR into PM6:Y6 binary blend could deactivate light-induced traps upon full sun illumination stress.…”

Incorporation of a Boron–Nitrogen Covalent Bond Improves the Charge-Transport and Charge-Transfer Characteristics of Organoboron Small-Molecule Acceptors for Organic Solar Cells

“…In OSCs, determining the energy-level alignment of an acceptor is particularly important since the key photovoltaic parameter V OC is dependent on the difference (Δ E DA ) between the LUMO energy level of the acceptor and the HOMO energy level of the donor (Δ E DA = E LUMO (A)− E HOMO (D)) [ 30 , 31 ], which is essential to drive devices [ 32 ]. As shown in Figure 2 a, M B←N and M B-N possess relatively higher-lying HOMO levels than that of M C-N , indicating less energy loss ( E loss ) in the boron-containing acceptors.…”

Two Well-Compatible Acceptors with Red-Shifted Absorption Edge and Cascaded LUMO Levels Enable Ternary Organic Photovoltaic Exhibiting Efficient Photovoltaic Performance

“…The J SC and V OC values under different illumination intensities are calculated from Figure S4 and shown in Figure . The relationship between J SC and the light intensity ( P light ) can be described as , β is an exponential factor. The β values are 0.969 and 0.972 for the PBDB-T-2F:FOIC binary OPV and optimized ternary OPV, respectively.…”