Thiophene–Arylamine Hole‐Transporting Materials in Perovskite Solar Cells: Substitution Position Effect

Abstract

Two facile thiophene–arylamine hole‐transporting materials, obtained by varying the substitution position of arylamine moieties on the thiophene π linker, are reported. The substitution position effect of two hole‐transporting materials on the performance of perovskite solar cells is further investigated theoretically and experimentally. The compound in which arylamine moieties are located on the 2,5‐substitution position of thiophene shows better conjunction than that with the 3,4‐substituent. When used as hole‐transporting materials in CH3NH3PbI3‐based solar cells, the 2,5‐substituent exhibits a power conversion efficiency (PCE) of 15.13 %, which is over 40 % higher than that of the 3,4‐substituent. Moreover, the PCE of 2,5‐substituent based device is comparable with that of 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene (spiro‐OMeTAD).

Positional Effect of the Triphenylamine Group on the Optical and Charge‐Transfer Properties of Thiophene‐Based Hole‐Transporting Materials

“…Recently, Dai et al. developed two new HTMs based on thiophene and triphenylamine, called H2,5 and H3,4 in their work . The substitution position effect of H2,5 and H3,4 on the performance of PSCs was studied.…”

“…Recently,D ai et al developed two new HTMs based on thiophene and triphenylamine, called H2,5 and H3,4 in their work. [11] The substitution positione ffect of H2,5 and H3,4 on the performance of PSCs was studied. Their resultss howed that PSC based on H2,5 exhibits aP CE of 15.13 %, while PCE is only 9.05 %b ased on H3,4.H erein, to explain the noteworthy different in PEC, we investigated geometries and electronic structure properties of H2,5 and H3,4.T wo molecular struc-Scheme1.Calculation procedureofh ole mobility.…”

“…In this work, we investigated the triphenylamine position effect of HTMs ( H2,5 and H3,4 from Dai's work) on the energy levels, optical properties, interaction of interface between HTM and perovskite, and hole transport behaviors using density functional theory and Marcus electron transfer theory. We showed that the planar structure not only increases hole mobility but also enhances the interfacial interactions of materials.…”

“…[9] We also investigated the influence of conjugate unit length on energy level and hole mobility,a nd we found that when the number of conjugate thiophtheneu nit is more than 4, the HOMO level is ac onstant,a nd molecule size ando dd or even number of thiophtheneu nit co-influence the hole transfer property. [10] In this work, we investigated the triphenylamine position effect of HTMs (H2,5 and H3,4 from Dai's work [11] )o nt he energy levels, opticalp roperties,i nteraction of interface between HTM and perovskite, and hole transport behaviors using density functional theory and Marcus electron transfer theory. We showed that the planar structure not only increases hole mobility but also enhances the interfacial interactions of materials.…”

Analysing the Prospects of Perovskite Solar Cells within the Purview of Recent Scientific Advancements

“…Wu et al developed electron rich HTMs with thiophene pi-linker claiming to reduce the synthesis cost by tenfold, in comparison with Spiro-OMeTAD, due to its shorter synthesis route [207]. Arylamine derivatives with pyrene core [208], two-dimensional triazatruxene-based derivatives [63], phenothiazine-based molecules [209], biphenyl based [210], bi-and tetra-thiophene based molecules [209,211], triazine based [212] HTMs could be a prospective replacement for Spiro-OMeTAD. Although polymeric HTMs such as PE-DOT:PSS and P3HT are proven to be cost effective, their polydispersity results in variation in the molecular weight for batch to batch production, hindering their commercialization [213].…”