Low‐Cost Carbazole‐Based Hole‐Transport Material for Highly Efficient Perovskite Solar Cells

Abstract

A low-cost carbazole-based small-molecule material, 1,3,6,8-tetra(N,N-p-dimethoxyphenylamino)-9-ethylcarbazole, was designed and synthesized through a facile three-step synthetic route. The material was characterized and applied as a hole-transport material (HTM) for low-temperature-processed planar perovskite solar cells (PSCs). Devices based on this new HTM exhibit a high power-conversion efficiency of 17.8 % that is comparable to that of PSCs based on the costly 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD) (18.6 %) .

Recent Advance in Solution‐Processed Organic Interlayers for High‐Performance Planar Perovskite Solar Cells

“…Carbazole‐based HTMs have been proven promising in both organic light‐emitting diodes and organic solar cells (OSCs) and also a main kind of small molecule HTMs in planar PSCs . This is owing to their excellent properties, such as cheap starting materials, strong electron‐donating property, suitable energy levels, special rigid structure, and large conjugated system, as well as the potential for structural modification by incorporation of different alkyl or functional groups into N atom or outer benzene ring of carbazole to tune optoelectronic properties, solubility, and molecular packing.…”

“…This is owing to their excellent properties, such as cheap starting materials, strong electron‐donating property, suitable energy levels, special rigid structure, and large conjugated system, as well as the potential for structural modification by incorporation of different alkyl or functional groups into N atom or outer benzene ring of carbazole to tune optoelectronic properties, solubility, and molecular packing. Chen et al reported a carbazole based small molecule material 1,3,6,8‐tetra(N,N‐p‐dimethoxyphenylamino)‐9‐ethyl‐carbazole(Cz‐OMeTAD, Figure ), which was synthesized with a facial synthetic route utilizing inexpensive, air‐stable, and nontoxic raw materials . With suitable energy levels, high mobility, and conductivity with dopants, Cz‐OMeTAD based PSCs showed a high PCE of 17.81%, analogous to that of Spiro‐OMeTAD based devices.…”

Hole-Transporting Materials for Printable Perovskite Solar Cells

“…Carbazole-based derivatives have attracted much attention as charge-transporting materials for organic light-emitting diodes (OLEDs), DSSCs and PSCs [ 101 , 102 , 103 ]. Their interesting photophysical properties such as intense luminescence and reversible oxidation processes, together with the reasonable synthetic costs, the versatility of the carbazole reactive sites and the excellent charge transport properties justify the efforts to find novel solutions for low-cost HTMs for PSCs in this class of compounds [ 10 , 40 , 82 , 83 , 84 , 86 , 87 , 88 , 89 , 90 , 91 , 92 ].…”

“…Simple enamine condensation chemistry for synthesis, low-cost materials and higher efficiency suggest the applicability of CA-XVI designs as HTMs for future high-performance and low-cost organic electronic devices. Chen et al reported a tetra-substituted carbazole-based HTM (CA-XVII; Figure 17 ) via a three-step synthesis, using low-cost starting materials, with a PCE of 17.81% [ 89 ]. The authors also investigated the role of the OMeTAD group in the system, by synthesizing a molecule similar to CA-XVII, but with a different substituent than OMeTAD.…”

Dopant-Free Hole Transport Materials with a Long Alkyl Chain for Stable Perovskite Solar Cells

“…The TPA group in particular can influence the optoelectrical properties of HTMs due to its non-planar geometry. Furthermore, the carbazole group has a high carrier mobility in OSCs and as good a performance as HTMs; thus, it is currently regarded as a core in PSCs [21,22,23,24,25,26,27].…”