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The design principles of acceptor1–acceptor2 copolymers featuring alternating diketopyrrolopyrrole (DPP) and thienopyrrolodione (TPD) moieties are investigated. The investigated series of polymers is obtained by varying the aromatic linker between the two acceptor motifs between thiophene, thiazole, pyridine, and benzene. High electron affinities between 3.96 and 4.42 eV, facilitated by the synergy of the acceptor motifs are determined with optical gaps between 1.37 and 2.02 eV. Grazing incidence wide-angle X-ray scattering studies reveal a range of film morphologies after thermal annealing, including face-on, end-on and superstructure edge-on-like crystallites. Conversely, all materials form thin edge-on layers on the polymer–air interface, as demonstrated by multi-elemental near-edge X-ray absorption fine-structure spectroscopy. The benefit of the electron-deficient linkers thiazole and pyridine is evident: In organic field effect transistors, electron mobilities of up to 4.6 × 10−2 cm2 V−1 s−1 are obtained with outstanding on/off current ratios of 5 × 105, facilitated by the absence of detectable hole transport in these materials. Viability for all-polymer solar cells is assessed in active layer blends with the donor polymer PM6, yielding a maximum average power conversion efficiency of 4.8% and an open circuit voltage above 1 V.

Solvent additives are pivotal for enhancing the morphology, efficiency, and stability of organic solar cells (OSCs). However, the widely used additive, 1,8‐diiodooctane (DIO), has drawbacks like harmful halogen content and potential OSC degradation. To address these issues, novel non‐halogenated, thienyl‐alkyl‐thienyl structural solvent additives—DTP, DTH, and DTN—featuring varying alkyl linker lengths of (CH2)3, (CH2)6, and (CH2)9, respectively are introduced. Additives with longer alkyl linkers, DTH and DTN, effectively dissolve and strongly interact with both the donor polymer PM6 and acceptor L8‐BO. This dual interaction enables precise tuning of their microstructures, resulting in enhanced crystallinity. Upon incorporating DTH as an additive in OSCs (PM6:L8‐BO), a minimal voltage loss is observed, leading to an impressive efficiency of 18.51%, surpassing the 17.90% achieved with DIO. Furthermore, DTH‐based devices demonstrated superior photostability. In a ternary blend system (PM6:D18‐Cl:L8‐BO), an efficiency of 19.07% is attained, outperforming previous non‐halogenated solvent additive‐based OSCs. Furthermore, employing a non‐halogenated processing solvent combination of toluene and carbon disulfide, a high PCE of 18.82% is achieved. These results underscore the efficacy of designing solvent additives with aromatic and alkyl units, enabling tailored interactions with the donor and acceptor, thereby presenting a robust strategy for optimizing OSC performance and stability. [ABSTRACT FROM AUTHOR]

The design principles of acceptor1–acceptor2 copolymers featuring alternating diketopyrrolopyrrole (DPP) and thienopyrrolodione (TPD) moieties are investigated. The investigated series of polymers is obtained by varying the aromatic linker between the two acceptor motifs between thiophene, thiazole, pyridine, and benzene. High electron affinities between 3.96 and 4.42 eV, facilitated by the synergy of the acceptor motifs are determined with optical gaps between 1.37 and 2.02 eV. Grazing incidence wide‐angle X‐ray scattering studies reveal a range of film morphologies after thermal annealing, including face‐on, end‐on and superstructure edge‐on‐like crystallites. Conversely, all materials form thin edge‐on layers on the polymer–air interface, as demonstrated by multi‐elemental near‐edge X‐ray absorption fine‐structure spectroscopy. The benefit of the electron‐deficient linkers thiazole and pyridine is evident: In organic field effect transistors, electron mobilities of up to 4.6 × 10−2 cm2 V−1 s−1 are obtained with outstanding on/off current ratios of 5 × 105, facilitated by the absence of detectable hole transport in these materials. Viability for all‐polymer solar cells is assessed in active layer blends with the donor polymer PM6, yielding a maximum average power conversion efficiency of 4.8% and an open circuit voltage above 1 V. [ABSTRACT FROM AUTHOR]

Polymer and small molecule blend thin films are of strong interest for organic electronics and particularly organic solar cells. The high miscibility in blends of ordinary P3HT and state‐of‐the‐art Y‐series non‐fullerene acceptors (NFAs) suppresses phase separation and aggregation challenging successful charge separation and transport. In a recent work, current‐induced doping (CID) is introduced, a method to precisely control the aggregation of Poly(3‐hexylthiophene) (P3HT) in solution. The highly ordered pre‐aggregation in solution is used here to control the P3HT aggregation in neat films and blends with Y12 (BTP‐4F‐12). This results in a 25‐fold increase in hole mobility in P3HT organic field‐effect transistor (OFET) devices and tunability of the P3HT aggregate quality in the presence of Y12 over large ranges. At the same time, particularly the Y12 long‐range ordering is heavily suppressed by increasing P3HT aggregation. However, solvent vapor annealing (SVA) leads to an extraordinarily high Y12 ordering, changes in the crystal orientation of Y12, and a further improvement of P3HT aggregation. A broad range of different degrees of aggregation of both materials can therefore be obtained in the final thin films solely by changing processing parameters without changing the composition of the material system. [ABSTRACT FROM AUTHOR]

The efficiency of an organic solar cell is highly dependent on the complex, interpenetrating morphology, and molecular order within the composite phases of the bulk heterojunction (BHJ) blend. Both these microstructural aspects are strongly influenced by the processing conditions and chemical design of donor/acceptor materials. To establish improved structure‐function relationships, it is vital to visualize the local microstructural order to provide specific local information about donor/acceptor interfaces and crystalline texture in BHJ blend films. The visualization of nanocrystallites, however, is difficult due to the complex semi‐crystalline structure with few characterization techniques capable of visualizing the molecular ordering of soft materials at the nanoscale. Here, it is demonstrated how cryo‐electron microscopy can be utilized to visualize local nanoscale order. This method is used to understand the distribution/orientation of crystallites in a BHJ blend. Long‐range (>300 nm) texturing of IEICO‐4F crystallites oriented in an edge‐on fashion is observed, which has not previously been observed for spin‐coated materials. This approach provides a wealth of quantitative information about the texture and size of nanocrystallites, which can be utilized to understand charge generation and transport in organic film. This study guides tailoring the material design and processing conditions for high‐performance organic optoelectronic devices. [ABSTRACT FROM AUTHOR]

The aggregation‐induced emission (AIE) properties of a systematic series of naphthalene diimides (NDIs) varying the chain length at the imide positions have been studied. A solvophobic collapse of NDI units through the flash injection of THF NDI solutions in sonicating water triggers the formation of stable suspensions with enhanced fluorescence emissions. Shorter chains favor the π‐π stacking of NDI units through H‐aggregation producing a strong AIE effect showing remarkably high quantum yields that have not been observed for non core‐substitued NDIs previously. On the other hand, NDIs functionalized with longer chains lead to more disordered domains where π‐π stacking between NDI units is mainly given by J‐aggregation unfavoring the AIE effect. [ABSTRACT FROM AUTHOR]