Encapsulation and Regeneration of Perovskite Film by in Situ Forming Cobalt Porphyrin Polymer for Efficient Photovoltaics

et al. 2021

Angew Chem Int Ed

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113

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.

Section: Figurementioning

confidence: 99%

Intramolecular Electric Field Construction in Metal Phthalocyanine as Dopant‐Free Hole Transporting Material for Stable Perovskite Solar Cells with >21 % Efficiency

et al. 2021

Angew Chem Int Ed

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113

“…Organic-inorganic hybrid perovskite materials have attracted tremendous attention owing to their low fabrication cost and intriguing optical and electronic properties. [1][2][3][4][5][6] The recently reported power conversion efficiency (PCE) of perovskite solar cells (PSCs) has exceed 25%. 7 However, during the fabrication of polycrystalline perovskite films under the solution-based preparation process, the inevitably formed large number of undersaturated metal or halide ions at the surface and grain boundaries (GBs) of perovskite film can act as ion migration paths.…”

Section: Introductionmentioning

confidence: 99%

“…[24][25][26] In our recent work, the ammonium/amine porphyrin or phthalocyanine macromolecules with excellent photoelectric properties was used to treat the perovskite film to obtain efficient surface and GBs modification and interfacial charge transfer, thus significantly enhancing the performance and stability of PSCs. 3,12,27 Since the defects mainly locate at the top surface of the perovskite film, 10,28 it is still a challenge to effectively encapsulate and modulate the perovskite surface to fabricate the efficient, stable, and environmental-friendly PSCs.…”

Section: Introductionmentioning

confidence: 99%

Lead and Iodide Fixation by Thiol Copper(II) Porphyrin for Stable and Environmental-Friendly Perovskite Solar Cells

Xiao

et al. 2021

CCS Chem

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The formation of undersaturated lead or iodide ions and I 2 on the perovskite surface can decrease the performance and stability of perovskite solar cells (PSCs). Additionally, the leakage of noxious lead limits the application of PSCs. Here, we develop a strategy for molecular modulation of a perovskite surface using thiol copper(II) porphyrin (CuP) to post-treat the perovskite film. The Raman spectra reveal that the CuP molecules anchor on the perovskite surface by a coordination interaction between the thiol-terminal of CuP and Pb ion in perovskite. DFT calculations demonstrate that the porphyrin core in CuP has a strong fixing effect on I − and I 2 by the induction force and electrostatic attraction. Such a fixation was demonstrated by the shift of the UV absorption peak of I 2 in solution with the addition of CuP and the decreased defects density in the CuP-treated perovskite film. Finally, the modified PSCs exhibit an improved cell performance with the best efficiency up to 21.76% (certified 20.97%). The modified PSCs acquired significantly improved stability. In addition, there is almost no lead leakage from the treated film immersed in water. This work provides a surface modulation strategy by thiol CuP treatment to fabricate efficient, stable, and environmental-friendly PSCs.

“…This would influence their charge transport behaviour within perovskite grain boundaries, which is unclear at the current stage.Porphyrins and their derivatives exhibit great thermal stability and good photoelectric properties, rendering them as the promising π-conjugated aromatic passivators. [19,[33][34][35] Here, we employ an amine copper porphyrin (CuP) to modify perovskite films. CuPs self-assemble into a supramolecule (CuP-S1) in perovskite grain boundaries.…”

mentioning

confidence: 99%

Homogeneously Large Polarons in Aromatic Passivators Improves Charge Transport between Perovskite Grains for >24 % Efficiency in Photovoltaics

Zhao

et al. 2022

Angewandte Chemie

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Aromatic passivators, such as porphyrin, with large π-backbones have attracted considerable attention to boost the charge carrier in polycrystalline perovskite films, thus enabling the fabrication of efficient and stable perovskite solar cells (PSCs). However, they often selfassemble into supramolecules that probably influence the charge-transfer process in the perovskite grain boundary. Here, by doping a monoamine Cu porphyrin into perovskite films, two porphyrin-based self-assembled supramolecules were successfully prepared between perovskite grains. Crystal structures and theoretical analyses reveal the presence of a stronger interaction between the amine units and the central Cu ions of neighbouring porphyrins in one of the supramolecules. This has a modified effect on the dipole direction of the porphyrins to be quantized as homogeneously large polarons (HLPs) in a periodic lattice. The porphyrin supramolecules can stabilize perovskite grain boundaries to greatly improve the stability of PSCs, while the HLPs-featured supramolecule facilitates hole transport across perovskite grains to remarkably increase the cell performance to as high as 24.2 %. This work proves that the modulation of the intermolecular interaction of aromatic passivators to yield HLPs is crucial for the cascaded acceleration of charge transport between perovskite grains. Organic-inorganic hybrid perovskite solar cells (PSCs)have attracted enormous attention because of their excellent power conversion efficiencies (PCEs) and low cost. [1][2][3][4] In recent years, the best PCE of PSCs has developed rapidly and has exceeded 25 %, approaching the single-junction Shockley-Queisser (SQ) limit. [5][6][7][8] A polycrystalline perovskite film fabricated by low-temperature solution-processed growth inevitably forms a large number of grain boundaries with a high defect density. [9][10][11][12] They are highly reactive to water and oxygen, thus inducing the degradation of the perovskite film and reducing the stability of PSCs. [13][14][15] These defects at grain boundaries acting as the recombination and trap-state centers are detrimental for the cell performance. [16][17][18] Thus, effective management of perovskite grain boundaries is vitally important for maximizing the performance and stability of PSCs. [19][20][21] A series of functional organic small molecules has been employed to passivate the perovskite defects and increase the performance and stability of PSCs. [22][23][24] However, these molecules have a high degree of volatility and high diffusion coefficients, resulting in poor stability under harsh environments, such as strong light, high temperature, and electric fields. [17,25] Stable aromatic passivators should be potential candidates to decorate perovskite films to promote the efficient charge transport across perovskite grains, [26][27][28][29][30][31] and/ or contribute to the surface band edges to influence the charge carrier dynamics, [32] thus leading to the fabrication of efficient and stable PSCs. It is worth noting that it is...