A Random Terpolymer Donor with Similar Monomers Enables 18.28% Efficiency Binary Organic Solar Cells with Well Polymer Batch Reproducibility

Abstract

Herein, by using two fluorinated and chlorinated monomers with similar structures in different molar ratios and dithieno­[3′,2′:3,4;2″,3″:5,6]­benzo­[1,2-c]­[1,2,5]­thiadiazole (DTBT) as the third unit, a family of polymer donors D18, D18–20%Cl, D18–40%Cl, and D18–Cl are synthesized for OSCs. With appropriate chlorinated monomer proportion, the terpolymer D18–20%Cl exhibits proper HOMO energy level and higher packing density compared with that of other control polymers. Moreover, the D18–20%Cl:Y6 blend films have favorable morphology with better face-on crystallization and better charge transport. Consequently, the D18–20%Cl:Y6-based OSCs obtain a top-ranked PCE of 18.28% with overall improved device parameters compared to the controlled D18:Y6 or D18-Cl:Y6-based OSCs (17.50% or 17.02%), which represents the highest PCE for the reported terpolymer-based binary OSCs. Notably, the D18–20%Cl:Y6-based OSCs exhibit over 17% efficiency in a wide molecular weight range. These results demonstrate that the ternary copolymerization of DTBT and two similar moieties is an efficient approach for achieving efficient terpolymer donors with well batch-to-batch reproducibility.

Molecular level understanding of the chalcogen atom effect on chalcogen-based polymers through electrostatic potential, non-covalent interactions, excited state behaviour, and radial distribution function

“…Polymer solar cells have gained widespread popularity due to their exclusive advantages, such as flexibility, solution processability and semitransparency. 1 The performance of organic solar cells has increased significantly. However, it has been the result of long-term hard work.…”

Composition-Tolerant Terpolymers for Efficient, Nonhalogenated Solvent-Processed Polymer Solar Cells

“…Among investigated PSCs, the DTTz-20:BTP-eC9 system achieved the highest PCE of 16.37% (open-circuit voltage ( V OC ) = 0.87 V, short-circuit current density ( J SC ) = 25.37 mA cm –2 , and fill factor (FF) = 74.1%), mainly due to its higher J SC and FF (Figure a and Table ). Interestingly, high PCE avg s (∼15%) were achieved in the devices based on DTTz-10 (14.75%), DTTz-20 (15.91%), DTTz-30 (15.40%), and DTTz-40 (15.12%) P D s. We consider that the good composition tolerance of the PSC performance is attributed to the structural similarity between the DTBT and DTTz units. ,, The effects of the structural similarity between the comonomers are discussed further in the blend morphology analysis. The external quantum efficiency (EQE) spectrum of each PSC and the corresponding calculated J SC are shown in Figure b.…”

Regioisomer‐Free Difluoro‐Monochloro Terminal‐based Hexa‐Halogenated Acceptor with Optimized Crystal Packing for Efficient Binary Organic Solar Cells

“…Thanks to the emergence of efficient polymeric donor and novel non‐fullerene acceptor materials with the optimization of device processing, significant progress has been achieved in OSCs [12–23] . At present, the design and synthesis of small molecular acceptors (SMAs) with A‐D‐A structure, especially for A‐DA'D‐A type SMAs, have occupied the dominant position in developing new acceptors, which have greatly improved the device performance of OSCs [24–34] . To achieve the goal of commercial application of OSCs, it is essential to develop more excellent SMAs and deeply understand the intermolecular packing of the SMAs and thereby further boost up the OSCs.…”