18.2%-efficient ternary all-polymer organic solar cells with improved stability enabled by a chlorinated guest polymer acceptor

New Type of Polymerized Small A-D-A Acceptors Constructed by Conjugation Extension in the Branched Direction

“…At present, almost all the high-performance PSMAs are constructed by directly polymerizing Y-series nonfullerene SMAs. , In the aspect of molecular structures, Y-series nonfullerene SMAs can be divided into three components: fused-ring central donors, electron-deficient terminals, and flexible branched chains. , Since the active sites for polymerization reactions usually locate at the electron-deficient terminals, it is not surprising that nearly all the high-performance PSMAs currently are constructed by polymerization through terminal units. , However, this pathway to construct PSMAs will bring about several inherent defects: (i) inferior intermolecular packings; the efficient molecular packings through terminal groups have been proven as the dominant packing mode in nonfullerene SMAs, which could be clearly concluded from lots of single-crystal structures of SMAs. ,, However, the chemical structure, electron-deficient property, and steric hindrance of terminal groups will be greatly changed when polymerizing with other linker units, such as thiophene or its derivatives, through terminal groups of SMAs. − This will inevitably damage the already perfect molecular packings formed by nonfullerene SMAs and, thus, decrease the PCEs of all-PSCs. (ii) Decreased halogen density; the polymerization through terminal units of SMAs will consume a halogen atom on molecular backbones.…”

“…20,21 Since the active sites for polymerization reactions usually locate at the electron-deficient terminals, it is not surprising that nearly all the highperformance PSMAs currently are constructed by polymerization through terminal units. 22,23 However, this pathway to construct PSMAs will bring about several inherent defects: (i) inferior intermolecular packings; the efficient molecular packings through terminal groups have been proven as the dominant packing mode in nonfullerene SMAs, which could be clearly concluded from lots of single-crystal structures of SMAs. 4,24,25 However, the chemical structure, electrondeficient property, and steric hindrance of terminal groups will be greatly changed when polymerizing with other linker units, such as thiophene or its derivatives, through terminal groups of SMAs.…”

An efficient polymer acceptor with fluorinated linkers enables all polymer solar cells with an efficiency of 15.7%

“…26–31 Recently, the PCEs of all-PSCs have reached 18%, narrowing the efficiency gap with SMA-based OSCs. 24,32…”

“…14,15 Encouraged by the rapid progress of Y-series SMAs, 16,17 researchers in this eld have been attracted to using Y-series SMAs to construct high-performance PSMAs. 6,14 Aerwards, many efforts were devoted to further developing PSMAs by modulating pconjugated fused-ring cores, [18][19][20] electron-decient end groups, [21][22][23][24][25] and p-linkers. [26][27][28][29][30][31] Recently, the PCEs of all-PSCs have reached 18%, narrowing the efficiency gap with SMAbased OSCs.…”

“…[26][27][28][29][30][31] Recently, the PCEs of all-PSCs have reached 18%, narrowing the efficiency gap with SMAbased OSCs. 24,32 Recent studies have conrmed that the molecular conformations of PSMAs play a crucial role in device performance. 23,33,34 For example, the commonly used thiophene linkers contribute to twisted molecular conformations and "randomness" to the polymer backbone, which negatively impact the properties of polymers.…”