Zn(II) and Cu(II) tetrakis(diarylamine)phthalocyanines as hole-transporting materials for perovskite solar cells

Finding new hole-transporting materials (HTMs) suitable for replacing the state-of-the-art spiro-OMe-TAD is still challenging. In this work, newly synthesized diarylamine-substituted metal phthalocyanines (MPcs, M 1/4 Zn(II) or Cu(II)) functionalized with either linear or branched alkoxy chains are evaluated as HTMs in perovskite solar cells. Both the nature of the alkoxy chains and that of the coordinated metal species were found to influence the functional properties of the new MPcs. In particular, devices based on a ZnPc featuring four n-butoxy side chains exhibited the highest power conversion efficiencies (PCEs). A PCE of 20.00% was reached for triple cation perovskite devices, and a PCE up to 20.18% could be achieved for double cation devices. (C) 2022 The Authors. Published by Elsevier Ltd.

Solid state nanocrystalline titanium oxide photovoltaic cells

The dye solar cell, is a novel photoelectrochemical solar cell presenting unique advantages, as the use of low cost materials and the potential simplicity of manufacturing. However, a liquid electrolyte is actually required for the transport of the photogenerated positive charges. A major breakthrough is the replacing of the liquid electrolyte by a solid-state hole conducting material – the aim of this work. First, the metal/TiO2 junction was investigated, with either silver or gold as rectifying contact. Sensitization was demonstrated, as action spectra were measured using different dyes. The evaporated metal could not enter the pores of the nanocrystalline TiO2 to contact all the dye molecules, hence only low photovoltaic performances were obtained. Furthermore, these metal/TiO2 junctions showed a high sensitivity to humidity and to forward bias polarization. The use of an electrically conducting polymer, poly(bithiophene), was studied in a metal/polymer junction and in TiO2/polymer devices with flat and nanocrystalline TiO2 electrodes. The photoelectric characterizations indicated that electrochemically reduced poly(bithiophene) was able to inject electrons into TiO2, i.e. sensitizing TiO2, and it acted as a hole conducting layer. Short-circuit current densities of 2-3 mA/cm2 were measured at an irradiation of 1.2 W/cm2. The open-circuit voltages were in the 250-350 mV range, depending on the light intensity and temperature. The use of a transparent hole conducting material, CuI, which is a wide bandgap p-type semiconductor, was demonstrated in a nanocrystalline junction made of highly porous sensitized TiO2 and solution-cast CuI. A short-circuit current of 1 mA/cm2 was achieved under one sun simulated light; the open-circuit voltage was 600 mV and the light-to-power conversion efficiency was 0.3 %. The peak quantum efficiencies of 8 % in the UV, and 3 % in the visible, showed that the nanocrystalline junction was working inefficiently, probably due to the poor electrical contact between the TiO2 nanocrystallites and the CuI crystals. Furthermore, the sensitizer was not tuned to inject holes into the valence band of CuI. As conclusion, a controlled-capillary pore based sensitized device is suggested. In this concept, all the internal surface of the TiO2 electrode coated with sensitizer is contacted with the transparent hole conducting layer, hence improving the photovoltaic properties of the device.

EPFL1996

Molecularly Engineered Phthalocyanines as Hole-Transporting Materials in Perovskite Solar Cells Reaching Power Conversion Efficiency of 17.5%

Kyung Taek Cho, Peng Gao, Giulia Grancini, Paul Gratia, Mohammad Khaja Nazeeruddin, Cristina Roldán Carmona, Olga Trukhina

Easily accessible tetra-5-hexylthiophene-, tetra-5-hexyl-2,2'-bisthiophene-substituted zinc phthalocyanines (ZnPcs) and tetra-tert-Bu ZnPc are employed as hole-transporting materials in mixed-ion perovskite [HC(NH2)2]0.85(CH3NH3)0.15Pb(I0.85Br0.15)3 solar cells, reaching the highest power conversion efficiency (PCE) so far for phthalocyanines. Results confirm that the photovoltaic performance is strongly influenced by both, the individual optoelectronic properties of ZnPcs and the aggregation of these tetrapyrrolic semiconductors in the solid thin film. The optimized devices exhibit PCE of 15.5% when using tetra-5-hexyl-2,2'-bisthiophene substituted ZnPcs, 13.3% for tetra-tert-Bu ZnPc, and a record 17.5% for tetra-5-hexylthiophene-based analog under std. global 100 mW cm-2 AM 1.5G illumination. These results boost up the potential of soln.-processed ZnPc derivs. as stable and economic hole-transport materials for large-scale applications, opening new frontiers toward a realistic, efficient, and inexpensive energy prodn.

2017

An Acetylene-Linked 9,9 '-Bicarbazole-Based Hole-Transporting Material for Efficient Perovskite Solar Cells

Jianxing Xia

A new hole-transporting material (XJ-05) based on a 9,9'-bicarbazole core and four acetylene-linked triphenylamine groups was designed and applied for perovskite solar cells (PSCs). Optical spectra, thermal stability, electrochemical properties, density functional theory calculations, hydrophobicity, hole mobility, hole transfer dynamics, and surface morphology of XJ-05 were evaluated and discussed. Planar n-i-p PSCs were fabricated using triple cation perovskite Cs-0.05(MA(0.17)FA(0.83))(0.95)Pb(I0.83Br0.17)(3) as the light-harvesting layer. The PSCs based on doped XJ-05 achieved a maximum power conversion efficiency (PCE) of 16.08%, which is comparable to that of PSCs based on state-of-the-art hole-transporting material, spiro-OMeTAD (17.55%). Unfortunately, the doped XJ-05-based cells showed inferior stability. Moreover, the dopant-free XJ-05-based devices showed a PCE up to 12.61% and retained 79.9% of their initial PCE under moisture after 260 h, which represent a much better stability than the spiro-OMeTAD-based ones.

AMER CHEMICAL SOC2022

Solid state nanocrystalline titanium oxide photovoltaic cells

EPFL1996

Zn(II) and Cu(II) tetrakis(diarylamine)phthalocyanines as hole-transporting materials for perovskite solar cells

Solid state nanocrystalline titanium oxide photovoltaic cells

Molecularly Engineered Phthalocyanines as Hole-​Transporting Materials in Perovskite Solar Cells Reaching Power Conversion Efficiency of 17.5​%

An Acetylene-Linked 9,9 '-Bicarbazole-Based Hole-Transporting Material for Efficient Perovskite Solar Cells

Solid state nanocrystalline titanium oxide photovoltaic cells

Molecularly Engineered Phthalocyanines as Hole-​Transporting Materials in Perovskite Solar Cells Reaching Power Conversion Efficiency of 17.5​%

An Acetylene-Linked 9,9 '-Bicarbazole-Based Hole-Transporting Material for Efficient Perovskite Solar Cells

Molecularly Engineered Phthalocyanines as Hole-Transporting Materials in Perovskite Solar Cells Reaching Power Conversion Efficiency of 17.5%

Molecularly Engineered Phthalocyanines as Hole-Transporting Materials in Perovskite Solar Cells Reaching Power Conversion Efficiency of 17.5%