Robust Nonspiro‐Based Hole Conductors for High‐Efficiency Perovskite Solar Cells

Abstract

Despite considerable development in performance, both poor operational stability and high costs associated with hole conductors such as 2,2′,7,7′‐tetrakis[N,N‐di(4‐methoxyphenyl)amino]‐9,9′‐spirobifluorene (spiro‐OMeTAD) and Poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine (PTAA) of perovskite solar cells (PSCs) need to be addressed by the research community. Here, two nonspiro hole transporting materials (HTMs), namely HTM‐1 and HTM‐2, are designed and straightforwardly synthesized exhibiting remarkable electrochemical properties and hole mobilities. In particular, the PSC based on the methoxy derivative (HTM‐2) exhibits a remarkable efficiency of 21.2% (stabilized efficiency of 20.8%), which is superior to the benchmark HTM spiro‐OMeTAD (stabilized efficiency of 20.4%). These results establish that the molecular design is effective in improving the performance of PSCs. Importantly, these two HTMs show admissible long‐term stability under different harsh conditions such as thermal stress up to 85 °C, high humidity level of 60% ± 10%, and continuous illumination over 1000 h. These insights allow correlating the impact of molecular design on optoelectronic properties of nonspiro‐based hole conductors with the overall device performance.

A New Vinylene-Thiophene-Vinylene Linked Triphenylamine-Phenothiazine Unsymmetrical D-π-D Small Molecule: Defect Passivation and Hole Transporting Interfacial Layer for Perovskite Solar Cells

“…A cyclic voltammogram for the molecule GS1 was obtained using the Origaflex OGF500 multichannel system with dry dichloromethane as a solvent and tetrabutylammonium hexafluorophosphate (NBu 4 PF 6 ) (0.1 M) as an electrolyte. The working electrode, reference electrode, and counter electrode are glassy carbon, silver–silver chloride, and platinum, respectively, and the energy levels were calculated according to the previously reported procedure . Fourier transform-infrared (FT-IR) data were obtained from the IR Tracer-100 Shimadzu system in the KBr mode.…”

“…The working electrode, reference electrode, and counter electrode are glassy carbon, silver−silver chloride, and platinum, respectively, and the energy levels were calculated according to the previously reported procedure. 36 Fourier transform-infrared (FT-IR) data were obtained from the IR Tracer-100 Shimadzu system in the KBr mode. XRD was performed on a Bruker D8 Advance X-ray diffractometer operating at 40 kV and 30 mA with a Cu Kα anode.…”

Organic‐inorganic hybrid material for hole transport in inverted perovskite solar cells

“…[34] However, due to their relatively low intrinsic conductivity and surface defects, inorganic HTMs fell short of the achievable PCE and their use is difficult in rigorous processing conditions. [35] Metal coordinated compounds have been used in photovoltaics for many years. [36] Initially, ruthenium(II) complexes such as N3 and N719 were used as photosensitizers in dye-sensitized solar cells, laying the groundwork for solar cells with very high performance.…”

“…These materials are pretty desirable as HTMs because they exhibit high air‐ambient stability and hole mobility [34] . However, due to their relatively low intrinsic conductivity and surface defects, inorganic HTMs fell short of the achievable PCE and their use is difficult in rigorous processing conditions [35] …”

Molecular engineering of methoxy-substituted terthienyl core unit based hole transport materials for perovskite solar cells

“…With more than a decade of development, the maximum certified power conversion efficiency (PCE) of perovskite solar cells (PSCs) has surged to 26.1%, and PSCs are considered as one of the most promising next-generation photovoltaic technologies. [1][2][3][4][5][6] Typically, high-performance PSC devices require the assistance of excellent hole transport materials (HTMs) with suitable energy levels, high hole mobility and conductivity to achieve efficient hole extraction and transport. [7][8][9][10][11][12][13] To date, 2,2 0 ,7,7 0 -tetrakis (N,N-di-pmethoxyphenylamine)-9,9 0 -spirobifluorene (Spiro-OMeTAD) is a state-of-art HTM that enables PSCs to achieve superior efficiency.…”