Doped Copper Phthalocyanine via an Aqueous Solution Process for Normal and Inverted Perovskite Solar Cells

Abstract

Great efforts toward developing novel and efficient hole‐transporting materials are needed to further improve the device efficiency and enhance the cell stability of perovskite solar cells (PSCs). The poor film conductivity and the low carrier mobility of organic small‐molecule‐based hole‐transporting materials restrict their application in PSCs. This study develops an efficient and stable hole‐transporting material, tetrafluorotetracyanoquinodimethane (F4‐TCNQ)‐doped copper phthalocyanine‐3,4′,4′′,4′′′‐tetra‐sulfonated acid tetra sodium salt (TS‐CuPc) via a solution process, in planar structure PSCs. The p‐type‐doped TS‐CuPc film demonstrates improved film conductivity and hole mobility owing to the strong electron affinity of F4‐TCNQ. By the F4‐TCNQ tailoring, the composite film gives the highest occupied molecular orbital level as high as 5.3 eV, which is beneficial for hole extraction. In addition, the aqueous solution processed TS‐CuPc:F4‐TCNQ precursor is almost neutral with good stability for avoiding the electrode erosion. As a result, the fabricated PSCs employing TS‐CuPc:F4‐TCNQ as the hole‐transporting material exhibit a power conversion efficiency of 16.14% in a p–i–n structure and 20.16% in an n–i–p structure, respectively. The developed organic small molecule of TS‐CuPc provides the diversification of hole‐transporting materials in planar PSCs.

Integrated molecular diode as 10 MHz half-wave rectifier based on an organic nanostructure heterojunction

“…These two factors lead to a large voltage drop over the diodes resulting in low outputs of the rectifiers 14 . There are at least two strategies for improving the electrical performance of CuPc: first, control the orientation of the planer molecules by modifying the surface of the substrate 8,17 , and second, rearrange the carrier distribution by introducing a heterojunction or dopants 18,19 . Previously, heterojunctions between metal phthalocyanines (MPcs) and fluorinated MPcs (F-MPcs) have been employed to enhance the carrier concentration by hybridization at the interface 20,21 .…”

Novel approaches and scalability prospects of copper based hole transporting materials for planar perovskite solar cells

“…A representative example is the demonstrated application of Cu HTMs (CuSCN and CuPc) in high efficiency and stability p-i-n PSCs, processed from aqueous media, a method that is forbidden from being applied in normal structure devices, since this would cause the immediate destruction of the perovskite film. 90,123 As demonstrated in Section 3, Cu derivatives are able to achieve devices with PCEs that compete with those offered by the typical organic HTMs that have been used so far, while at the same time exhibiting higher stability and reduced cost. In addition, their energy levels can be easily tailored to match all of the different perovskite compositions, rendering these materials appropriate for a wide range of applications, such as light emission and lasing, apart from solar cells.…”

“…The CuPc derivative Cu phthalocyanine-3,4 0 ,4 0 0 ,4 0 0 0 -tetrasulfonated acid tetra sodium salt (TS-CuPc) possesses good solubility in polar solvents, which allows its application as a HTL in low-cost PSCs. By using an aqueous solution process Wang et al 123 have prepared composite films of Cu phthalocyanine-3,4 0 ,4 0 0 ,4 0 0 0 -tetra-sulfonated acid tetra sodium salt (TS-CuPc), doped with tetrafluoro tetracyanoquinodimethane (F 4 -TCNQ) with improved film conductivity and hole mobility. These films have been then incorporated in inverted structure CH 3 NH 3 PbI 3 PSCs that yielded efficiencies of 16.14%, with a simultaneous increase of both current density and open circuit voltage, compared to the reference PEDOT:PSS device that reached 12.88% PCE in the same system.…”

Carbon‐Electrode Based Perovskite Solar Cells: Effect of Bulk Engineering and Interface Engineering on the Power Conversion Properties

“…It should be noted that there exists a large amount of efficient bulk/interface engineering strategies . These progresses are worthy to be carefully studied.…”