A New Polymer Donor Enables Binary All‐Polymer Organic Photovoltaic Cells with 18% Efficiency and Excellent Mechanical Robustness

Abstract

The development of polymerized small‐molecule acceptors has boosted the power conversion efficiencies (PCEs) of all‐polymer organic photovoltaic (OPV) cells to 17%. However, the polymer donors suitable for all‐polymer OPV cells are still lacking, restricting the further improvement of their PCEs. Herein, a new polymer donor named PQM‐Cl is designed and its photovoltaic performance is explored. The negative electrostatic potential and low average local ionization energy distribution of the PQM‐Cl surface enable efficient charge generation and transfer process. When blending with a well‐used polymer acceptor, PY‐IT, the PQM‐Cl‐based devices deliver an impressive PCE of 18.0% with a superior fill factor of 80.7%, both of which are the highest values for all‐polymer OPV cells. The relevant measurements demonstrate that PQM‐Cl‐based films possess excellent mechanical and flexible properties. As such, PQM‐Cl‐based flexible photovoltaic cells are fabricated and an excellent PCE of 16.5% with high mechanical stability is displayed. These results demonstrate that PQM‐Cl is a potential candidate for all‐polymer OPV cells and provide insights into the design of polymer donors for high‐efficient all‐polymer OPV cells.

Y-Series-Based Polymer Acceptors for High-Performance All-Polymer Solar Cells in Binary and Non-binary Systems

“…New polymer or small-molecule donors with complementary absorptions, suitable energy levels, crystallinity, and miscibility with Y-series-based polymer acceptors should be designed to simultaneously improve the V oc , J sc , and FF of the resulting PSCs. To acquire high-performance D-A copolymer donors, the development of acceptor moieties based on quinoxaline (PBQx-H-TF and PQM-Cl) , or imide (PTzBI- o F and Q4) , has been proven a feasible method. The Same-A-Strategy using BT moieties (D18 and JD40) , can be applied to ensure good miscibility between polymer donors and Y-series-based polymer acceptors.…”

“…The corresponding Y-series-based polymer acceptors also overcome the limitations of D-A-type and A-D-A-type polymer acceptors by reducing the energy loss for high short-circuit current density ( J sc ) and open-circuit voltage ( V oc ) and by suppressing unfavorable charge-transfer states and charge carrier recombination. − Since the first Y-series-based polymer acceptor was reported by Huang et al in 2020, this type of acceptors was deemed the best n-type materials. Very recently, all-PSCs containing Y-series-based polymer acceptor achieved a high PCE of 18%, comparable to that of Y-series SMA-based devices. , Nevertheless, if flexible organic solar cells (OSCs) are to be considered in the future, the continuous development of a new polymer acceptor with superior thermal and mechanical stability is necessary. For such research, it is of the utmost importance to examine exhaustively all approaches utilized in the past three years with all-PSCs comprising polymer acceptors based on the Y-series SMAs.…”

Recent Advances in Single‐Junction Organic Solar Cells

“…When the PSMA strategy was used for Y6 molecules, [57][58][59][60][61][62] the PCEs increased to over 18 %. [63] Note that the M n s are usually lower than 15 kDa for Y6-based highly efficient PSMA acceptors, corresponding to a repeat unit number of � 10. The impact of molecular weight, PDI, and chain conformation on photovoltaic performance should be carefully studied.…”

Sequential Processing Enables 17% All-Polymer Solar Cells via Non-Halogen Organic Solvent

“…Due to their similar advantages to small molecule acceptor-based OSCs, All-PSCs possess better mechanical properties, such as higher tensile and flexural toughness, and potentially higher thermal stability, which give them better prospects for mass production [ 18 , 19 , 20 ]. Recently, the strategy of polymerized small molecule acceptors (PSMAs) has boosted the efficiency of All-PSCs to over 17% [ 21 , 22 ]. However, most of the high PCEs for these all-PSCs have been based on active layers that were processed from either chloroform (CF) or a CF-dominant solvent mixture [ 20 , 23 , 24 ].…”