Triisopropylsilyl‐Substituted Benzo[1,2‐b:4,5‐c′]dithiophene‐4,8‐dione‐Containing Copolymers with More Than 17% Efficiency in Organic Solar Cells

Abstract

Considering the special functions of fused-ring aromatic building blocks and Si-atom in high-performance donor-acceptor-conjugated materials at the same time, herein the synthesis of a novel fused-ring tricyclic heterocycle, triisopropylsilyl-substituted benzo[1,2-b:4,5-c′]dithiophene-4,8-dione (iBDD-Si), an isomer of well-known benzo[1,2-c:4,5-c′]dithiophene-4,8-dione is presented. The iBDD-Si-based copolymer series (PM6, PM6-5Si, PM6-10Si, and PM6-15Si) is synthesized via Stille polymerization, revealing fine-tuned optical and electrochemical properties, and molecular packing with varying iBDD-Si contents in the backbone. Organic solar cells are fabricated by pairing the copolymer donors with nonfullerene acceptor N3 and characterized. High power conversion efficiency of more than 17% is achieved using the PM6-5Sibased solar cell, which is attributed to the balanced charge transport, enhanced charge generation/dissociation kinetics, and minimized total energy and recombination losses. It is demonstrated that iBDD-Si is a promising backbone toolbox for various high-performance conjugated materials.

Random Copolymerization Strategy for Host Polymer Donor PM6 Enables Improved Efficiency Both in Binary and Ternary Organic Solar Cells

“…The unusual trend for the PM6-TPD-10 % : Y6-based device is mainly due to the nonradiative recombination, which is consistent with the V OC of the corresponding OSCs. [21] We further fabricated ternary devices to investigate the influence of PM6-TPD-5 % contents on the photovoltaic performance. As shown in Figure S11, by incorporating PM6-TPD-5 % into the PM6:Y6, PCE was boosted to 17.1 % with a V OC of 0.862 V, J SC of 26.07 mA cm À 2 , and an FF of 76.15 % at the optimal ratio of PM6-TPD-5 % : PM6 is 0.05 : 0.95 (Table 2).…”

“…From the perspective of polymer donors, optimizing structures and adjusting the chemical structures by molecular reconstruction or modification of the building blocks has proved to be an effective method, such as introducing electronwithdrawing groups or modification of the side chains. [18][19][20][21][22] However, both molecular reconstruction and structural modification normally depend on deliberate molecular design and bring tedious synthesis. [23] Random copolymerization has emerged as a promising synthetic strategy for fine-tuning the electronic energy levels, optical properties, and molecular configuration of polymer backbones by introducing the third unit (D2 or A2) into the D-A binary copolymer.…”

Isogenous Asymmetric–Symmetric Acceptors Enable Efficient Ternary Organic Solar Cells with Thin and 300 nm Thick Active Layers Simultaneously

“…[29,30] Ternary strategy plays a versatile role in potentially optimizing the energy level, fine-tuning the morphology, and enhancing the charge mobilities, which can elevate thickness tolerance for PCE of OSCs. [31] Therefore, the logical selection of the third component for integrating multiple benefits in one ternary system is the kernel to construct efficient OSCs with the thickness-insensitive feature for the future commercialized application. However, over 16% PCE of ternary OSCs with 300 nm thick film has been rarely reported; [32] there is large room to develop efficient ternary OSCs with thin and thick active layers simultaneously.…”

Conjugated Mesopolymer Achieving 15% Efficiency Single‐Junction Organic Solar Cells

“…[ 8 ] Some reports have showed that PM6 with high molecular weight can produce high PCE of over 17%. [ 33 , 34 , 35 , 36 , 37 , 38 ] But the efficient PM6 batch must react in a mixed solvents of toluene and DMF system, which is difficult to control in molecular weight consistency. As far as D18, only in a narrow number‐averaged molecular weight (Mn) range about 70 kDa can exhibit relatively high efficiency for corresponding PSC device.…”