Low conductivity and hole mobility in the pristine metal phthalocyanines greatly limit their application in perovskite solar cells (PSCs) as the hole‐transporting materials (HTMs). Here, we prepare a Ni phthalocyanine (NiPc) decorated by four methoxyethoxy units as HTMs. In NiPc, the two oxygen atoms in peripheral substituent have a modified effect on the dipole direction, while the central Ni atom contributes more electron to phthalocyanine ring, thus efficiently increasing the intramolecular dipole. Calculation analyses reveal the extracted holes within NiPc are mainly concentrated on the phthalocyanine core induced by the intramolecular electric field, and further to be transferred by π‐π stacking space channel between NiPc molecules. Finally, the best efficiency of PSCs with NiPc as dopant‐free HTMs realizes a record value of 21.23 % (certified 21.03 %). The PSCs also exhibit the good moisture, heating and light stabilities. This work provides a novel way to improve the performance of PSCs with free‐doped metal phthalocyanines as HTMs.
Inhibiting the ions migration and even irreversible reactions have been regarded as one of the most important factors for fabricating efficient and stable perovskite solar cells (PSCs). Here, we employed the diamine cobalt(II) porphyrin [Co(II)P] to treat a perovskite film to construct in situ Co(II)P-based coordination polymer on the perovskite film. The crystal structure of the polymer indicated a central cobalt (Co) ion in one Co(II)P coordinated with two amine units from a different neighboring Co(II)P to form an overall three-dimensional (3D) structure. Such a 3D network covered on the perovskite surface could prevent the migration of ions from the perovskite. Furthermore, the limited amount of diatomic iodine (I 2 ) released in the perovskite due to iodide oxidation defects could be reduced to Iby the Co(II) ion in the polymer, and thus, achieve regeneration. Finally, the Co(II/III) ion pair formed in the polymer facilitated the charge transfer and boosted to the best efficiency up to 21.3%. Remarkably improved cell stability under moisture, heating, or light was also achieved.The control PSCs with Zn-based 3D polymer and Co-based 1D polymer exhibited the poor cell efficiencies and stabilities than those of the 3D Co porphyrin-based PSC to verify the effect of 3D Co porphyrin-based polymer in stabilizing the perovskite film. This work provides a new encapsulation and regeneration strategy via in situ construction of a Co(II) porphyrin-based coordination polymer on perovskite film for efficient and stable PSCs.
The fabrication of high‐performance nonvolatile organic field effect transistor (OFET) memory devices is reported using a series of pyrene‐fused pyrazaacene (PPA) and 9,10‐imide‐pyrene‐fused pyrazaacene (IPPA) derivatives as n‐type doping components. The obtained memory devices exhibit stable switching behaviors (>100 times) and good retention properties (>104 s). Devices based on chlorinated IPPA (IPPA‐Cl) show the largest memory window of 40.8 V, with a trapping charge density of 2.66 × 1012 cm−2 and on/off ratio higher than 106. Our investigation reveals that low‐lying lowest unoccupied molecular orbital energy levels and small dipole moment are key parameters for achieving high memory performance. This work provides a general guideline for the design of n‐type organic semiconductors as highly efficient doping materials for organic memory devices.
Low conductivity and hole mobility in the pristine metal phthalocyanines greatly limit their application in perovskite solar cells (PSCs) as the hole‐transporting materials (HTMs). Here, we prepare a Ni phthalocyanine (NiPc) decorated by four methoxyethoxy units as HTMs. In NiPc, the two oxygen atoms in peripheral substituent have a modified effect on the dipole direction, while the central Ni atom contributes more electron to phthalocyanine ring, thus efficiently increasing the intramolecular dipole. Calculation analyses reveal the extracted holes within NiPc are mainly concentrated on the phthalocyanine core induced by the intramolecular electric field, and further to be transferred by π‐π stacking space channel between NiPc molecules. Finally, the best efficiency of PSCs with NiPc as dopant‐free HTMs realizes a record value of 21.23 % (certified 21.03 %). The PSCs also exhibit the good moisture, heating and light stabilities. This work provides a novel way to improve the performance of PSCs with free‐doped metal phthalocyanines as HTMs.
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