Study of Arylamine-Substituted Porphyrins as Hole-Transporting Materials in High-Performance Perovskite Solar Cells

Abstract

To develop new hole-transporting materials (HTMs) for efficient and stable perovskite solar cells (PSCs), 5,10,15,20-tetrakis{4-[N,N-di(4-methoxylphenyl)amino-phenyl]}-porphyrin was prepared in gram scale through the direct condensation of pyrrole and 4-[bis(4-methoxyphenyl)amino]benzaldehyde. Its Zn(II) and Cu(II) complexes exhibit excellent thermal and electrochemical stability, specifically a high hole mobility and very favorable energetics for hole extraction that render them a new class of HTMs in organometallic halide PSCs. As expected, ZnP as HTM in PSCs affords a competitive power conversion efficiency (PCE) of 17.78%, which is comparable to that of the most powerful HTM of Spiro-MeOTAD (18.59%) under the same working conditions. Meanwhile, the metal centers affect somewhat the photovoltaic performances that CuP as HTM produces a lower PCE of 15.36%. Notably, the PSCs employing ZnP show a much better stability than Spiro-OMeTAD. Moreover, the two porphyrin-based HTMs can be prepared from relatively cheap raw materials with a facile synthetic route. The results demonstrate that ZnP and CuP can be a new class of HTMs for efficient and stable PSCs. To the best of our knowledge, this is the best performance that porphyrin-based solar cells could show with PCE > 17%.

Intensive Exposure of Functional Rings of a Polymeric Hole‐Transporting Material Enables Efficient Perovskite Solar Cells

“…To avoid this trade‐off between photovoltaic properties and long‐term stability and to circumvent the tight control of doping level and oxidation duration in the fabrication procedure, numerous dopant‐free HTMs including small molecules and conjugated polymers have been vigorously explored, and the exploration mainly focused on the following three characteristics of HTMs: 1) long‐term stability when exposed to air, 2) suitable frontier energy levels matching that of perovskite layer, and 3) a high intrinsic hole mobility to deliver the photogenerated holes to the electrode. Generally, an HTM without any dopants could easily meet the former two requirements with proper frontier energy levels via engineering the side‐chain, finely tuning the position of functional groups and/or substituting atoms in the aromatic rings .…”

Dopant‐Free Hole Transporting Materials for Perovskite Solar Cells

“…Two novel symmetric ethynylaniline‐substituted porphyrin based HTMs Y2 ( 125 ) and Y2A2 ( 126 ), have been employed in conventional planar PSCs and PCEs of 16.60 and 10.55% have been measured, respectively . In 2017, Chen et al have developed CuP ( 127 ) and ZnP ( 128 ), two arylamine‐substituted porphyrin based HTMs for perovskite devices . Efficient and stable PSCs have been fabricated with PCEs as high as 15.36 and 17.78% for CuP and ZnP based devices, respectively.…”

o,p‐Dimethoxybiphenyl Arylamine Substituted Porphyrins as Hole‐Transport Materials: Electrochemical, Photophysical, and Carrier Mobility Characterization

“…On the one hand, the symmetric substitution of the porphyrin using o,p-dimethoxybiphenyl arylamine moieties will increase the porphyrin solubility and will be helpful to obtain organic thin films. [13] Careful analysis of a set of high-resolution NMR spectra acquired for the crude reaction confirmed a polymerization reaction between aldehyde 3 and pyrrole took place instead of porphyrinogen formation. The detailed synthetic route to the porphyrins is shown in Scheme 1.…”

“…The crude product was purified by column chromatography over silica gel with DCM as the eluent and subsequent recrystallization H) ppm 13. The reaction mixture was degassed three times using freeze-thaw cycles and then the reaction mixture was stirred at 50°C for 14 h. After cooling to room temperature, distilled water was added and the mixture was extracted with DCM three times.…”