Simple Is Best: A p-Phenylene Bridging Methoxydiphenylamine-Substituted Carbazole Hole Transporter for High-Performance Perovskite Solar Cells

Abstract

Methoxydiphenylamine-substituted carbazole (MODPACz) is widely used to construct hole-transporting materials (HTMs) for perovskite solar cells (PSCs), whose performances rely highly on the linking way of the MODPACz units and the simplicity of the π-bridge. In this paper, we report a new HTM, pPh-2MODPACz, using one of the simplest πbridges p-phenylene to link the MODPACz units. The structural feature endows pPh-2MODPACz with high hole mobility and conductivity, efficient hole extraction ability, and good film-forming property. MAPbI 3 -based PSCs using doped and undoped pPh-2MODPACz as the HTM offer efficiencies of ∼20% and 16.07%, respectively; both are better than those of the devices with spiro-OMeTAD as the HTM. The device stability of pPh-2MODPACz-based PSCs is also greatly enhanced. This work demonstrates that the simplest p-phenylene bridge for linking MODPACz can derive a promising HTM with a high device performance, providing a distinctive pathway to develop new HTMs.

Development of Dopant‐Free Organic Hole Transporting Materials for Perovskite Solar Cells

“…Several of the structures, irrespective of the device architecture, show reasonable performance and equivalent hole mobilities of the order 10 −3 cm 2 V −1 s −1 , which is on the higher range of typical polymeric HTMs (10 −3 –10 −5 cm 2 V −1 s −1 ). Interestingly, it should be noted exceptional examples included PTEG (16.4 × 10 −4 cm 2 V −1 s −1 ), P1 (17.2 × 10 −4 cm 2 V −1 s −1 ), M118 (17.5 × 10 −4 cm 2 V −1 s −1 ), pBBTa‐BDT2 (20 × 10 −4 cm 2 V −1 s −1 ), RCP (30.9 × 10 −4 cm 2 V −1 s −1 ), and R1 (37 × 10 −4 cm 2 V −1 s −1 ) . Structural observations showed that few were purely of a nitrogen heterocyclic nature, i.e., M118, with several of the more exceptional performances containing thiophene, i.e., pBBTa‐BDT2, and several with extended conjugation and polymeric backbones, i.e., R1, PTEG, and RCP, which showed enhanced performance over small molecular and larger branched molecular structures.…”

“…Interestingly, it should be noted exceptional examples included PTEG (16.4 × 10 −4 cm 2 V −1 s −1 ), [87] P1 (17.2 × 10 −4 cm 2 V −1 s −1 ), [85] M118 (17.5 × 10 −4 cm 2 V −1 s −1 ), [84] pBBTa-BDT2 (20 × 10 −4 cm 2 V −1 s −1 ), [4] RCP (30.9 × 10 −4 cm 2 V −1 s −1 ), [77] and R1 (37 × 10 −4 cm 2 V −1 s −1 ) . [131] Structural observations showed that few were purely of a nitrogen heterocyclic nature, i.e., M118, with several of the more exceptional performances containing thiophene, i.e., pBBTa-BDT2, and several with extended conjugation and polymeric backbones, i.e., R1, PTEG, and RCP, which showed enhanced performance over small molecular and larger branched molecular structures. This indicates that high hole mobility (10 −1 -10 −2 cm 2 V −1 s −1 ) in dopant free HTMs may not be as critical as achieving optimum structures that extend conjugation with functional groups that enable better interaction between device layers.…”

“…Meanwhile, hysteresis free small scaled devices based on XY1 showed a competitive PCE of 18.78%. Further, several novel chemical structures of dopant‐free HTMs with moderate device data have been reported (summarized in Table 1 and 2) yet not discussed in detail here …”

Pyridine Bridging Diphenylamine-Carbazole with Linking Topology as Rational Hole Transporter for Perovskite Solar Cells Fabrication

“…The 2,6PyDANCBZ and 3,5PyDANCBZ exhibit a high glass transition temperature (Tg) of 132 and 126 °C, respectively, which are higher than that of Spiro-OMeTAD. 48 The notable high Tg shown by HTMs will prevent any phase change process, suggesting the functioning of devices in the temperature window required for commercial validation. calculated from the slope of the J 1/2 -V curves ( Figure S3) according to Mott-Gurney law (J=9εε0µVapp 2 /8L 3 ) and the data were collected in Table 1.…”

Recent Advances in Organic Hole Transporting Materials for Perovskite Solar Cells

“…Low‐cost methoxydiphenylamine‐substituted carbazole (MODPACz) is mostly used at the peripheral of HTMs for PSCs, whose performances highly rely on the linking way of the MODPACz units. [ 42 ] The simplest way is to connect by phenyl bridge, and the molecules based on this configuration demonstrate reasonable hole mobility and conductivity, feasible synthesis, and good film‐forming capability, all leading to a PCE over 20% in PSCs with MAPbI 3 and planar device structure. Because of good conductivity, these HTMs showed a high PCE of 16.07% in devices without adding HTM, which is much better than the devices with the classical spiro‐OMeTAD.…”