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Abstract Mechanically deformable polymeric semiconductors are a key material for fabricating flexible organic thin‐film transistors (FOTFTs)—the building block of electronic circuits and wearable electronic devices. However, for many π‐conjugated polymers achieving mechanical deformability and efficient charge transport remains challenging. Here the effects of polymer backbone bending stiffness and film microstructure on mechanical flexibility and charge transport are investigated via experimental and computational methods for a series of electron‐transporting naphthalene diimide (NDI) polymers having differing extents of π‐conjugation. The results show that replacing increasing amounts of the π‐conjugated comonomer dithienylvinylene (TVT) with the π‐nonconjugated comonomer dithienylethane (TET) in the backbone of the fully π‐conjugated polymeric semiconductor, PNDI‐TVT₁₀₀(yielding polymeric series PNDI‐TVT_x, 100 ≥x≥ 0), lowers backbone rigidity, degree of texturing, and π–π stacking interactions between NDI moieties. Importantly, this comonomer substitution increases the mechanical robustness of PNDI‐TVT_xwhile retaining efficient charge transport. Thus, reducing the TVT content of PNDI‐TVT_xsuppresses film crack formation and dramatically stabilizes the field‐effect electron mobility upon bending (e.g., 2 mm over 2000 bending cycles). This work provides a route to tune π–π stacking in π‐conjugated polymers while simultaneously promoting mechanical flexibility and retaining good carrier mobility in FOTFTs. 

Abstract All‐inorganic CsPbI₃quantum dots (QDs) have shown great potential in photovoltaic applications. However, their performance has been limited by defects and phase stability. Herein, an anion/cation synergy strategy to improve the structural stability of CsPbI₃QDs and reduce the pivotal iodine vacancy (V_I) defect states is proposed. The Zn‐doped CsPbI₃(Zn:CsPbI₃) QDs have been successfully synthesized employing ZnI₂as the dopant to provide Zn²⁺and extra I⁻. Theoretical calculations and experimental results demonstrate that the Zn:CsPbI₃QDs show better thermodynamic stability and higher photoluminescence quantum yield (PLQY) compared to the pristine CsPbI₃QDs. The doping of Zn in CsPbI₃QDs increases the formation energy and Goldschmidt tolerance factor, thereby improving the thermodynamic stability. The additional I⁻helps to reduce theV_Idefects during the synthesis of CsPbI₃QDs, resulting in the higher PLQY. More importantly, the synergistic effect of Zn²⁺and I⁻in CsPbI₃QDs can prevent the iodine loss during the fabrication of CsPbI₃QD film, inhibiting the formation of newV_Idefect states in the construction of solar cells. Consequently, the anion/cation synergy strategy affords the CsPbI₃quantum dot solar cells (QDSC) a power conversion efficiency over 16%, which is among the best efficiencies for perovskite QDSCs.