The Insolubility Problem of Organic Hole-Transport Materials Solved by Solvothermal Technology: Toward Solution-Processable Perovskite Solar Cells

Abstract

Generally, the high efficiency of solution-processable perovskite solar cells (PSCs) comes at the expense of using expensive organic matters as a hole-transport material (HTM). Although intense efforts have tried to use commercially available and low-cost macrocyclic molecules as HTM candidates, they still face two enormous challenges: poor solubility and inherent instability. Here, solvothermal treatment for old and insoluble HTMs (phthalocyanine (Pc) and its derivatives) has been proposed, which is unusual due to the occurrence of solubilization for insoluble precursors induced by the carbonization of the dissolved part. Since the macrocyclic structure still exists, the as-prepared new-type carbon dots not only retain the capacity of hole transfer but serve as an effective passivation additive. Synergy makes the all-air-processed carbon-based PSCs (CH3NH3PbI3) fabricated with carbon dots achieve a decent power conversion efficiency of 13.7%. Importantly, organics have undergone solvothermal treatment, completely breaking through the instability bottleneck, which exists in the long-term operation of PSCs. The universality of this methodology will usher exploration into other low-cost insoluble organics and drastically enhance the high-performance cost ratio of PSC equipment.

Construction of a Highly Anisotropic Supramolecular Assembly Assisted by a Dimensional Confinement Space: Toward Perovskite Solar Cells

“…For the dense TiO 2 layer, 0.4 M titanium tetraisopropoxide was dissolved in ethanol and spin-coated onto FTO at 1000 rpm for 3 s and at 2500 rpm for 30 s. For the mesoporous TiO 2 layer, the mesoporous TiO 2 slurry was dissolved in ethanol and spin-coated on the dense TiO 2 layer at 1000 rpm for 3 s and at 3500 rpm for 30 s, followed by sintering at 500 °C for 30 min. The preparation of PVK films refers to our previous report . In short, the PVK precursor solution was prepared by adding MAI and PbI 2 in the same molar ratio to a mixed solution of DMF and DMSO with a volume ratio of 10:1.…”

“…The preparation of PVK films refers to our previous report. 34 In short, the PVK precursor solution was prepared by adding MAI and PbI 2 in the same molar ratio to a mixed solution of DMF and DMSO with a volume ratio of 10:1. PVK thin films were deposited on mesoporous TiO 2 layers by spin coating at 1000 rpm for 10 s and at 4000 rpm for 20 s. In the second spin-coating step, 200 μL of PDI assembly stock solution was dropped onto the substrate.…”

Carbon‐Dot‐Mediated Highly Efficient Visible‐Driven Photocatalytic Hydrogen Evolution Coupled with Organic Oxidation

“…[22] Meanwhile, the metal phthalocyanines and carbon dots (CDs) have been intensively applied in photocatalysis and electrocatalysis as multifunctional model catalysts, including hydrogen production and CO 2 reduction. [23][24][25][26][27][28] Here, we introduced nickel phthalocyanine (NiPc)-CDs as hole acceptors to modify the Cu-In-Zn-S QDs and to construct an efficient ternary photocatalyst for PHECOO toward a profound understanding of the charge separation kinetics and surface oxidation reaction processes. NiPc was used in photocatalysis as a hole extraction material for the first time by combining with CDs to obtain NiPc-functionalized CDs with largely promoted hole accepting capability.…”

Insoluble Organics as Electron-Transporting Materials Enabled by Solvothermal Technology for Solution-Processable Perovskite Solar Cells

“…According to our previous work, solvothermal technology has shown its unique advantage in solving solubility problems and energy matching of hole-transporting materials. 29 Here, the solvothermal technology is used to treat PDI molecules to ETMs (PDI-CDs) that can be used in n-i-p-type PSC devices by combining the two processes of solubilization and carbonization. After optimization, the champion PSC device with the PDI-CD interfacial layer achieved a maximum PCE of 11.90%.…”