Near-Ultraviolet Transparent Organic Hole-Transporting Materials Containing Partially Oxygen-Bridged Triphenylamine Skeletons for Efficient Perovskite Solar Cells

Abstract

Organic semiconducting materials that are optically transparent in the near-ultraviolet (NUV) region from 300 to 400 nm are needed for advanced perovskite devices such as bifacial semitransparent and tandem solar cells. In this study, three organic semiconducting materials, HND-NAr 2 , HND-DTP, and HND-Cbz, were designed and synthesized by introducing bis(4methoxyphenyl)amine, dithieno[3,2-b:2′,3′-d]pyrrole, and carbazole, respectively, into the head position of partially oxygenbridged triphenylamine skeletons. The combination of oxygenbridged triphenylamine and an electron-donating group at the head position suppresses the π−π* transition, leading to weak absorption in the NUV region. Thin films of the materials can be fabricated by both solution and vacuum-deposition processes, and applied as the hole-transporting material (HTM) in perovskite solar cells (PSCs). The power conversion efficiency (PCE) of conventional devices with these HTMs was 13.7% (HND-Cbz), 15.0% (HND-DTP), and 17.2% (HND-NAr 2 ). When used in bifacial semitransparent PSCs, the incident photon-to-current conversion efficiency (IPCE) at 400 nm was 41% (HND-NAr 2 ), 45% (HND-Cbz), and 46% (HND-DTP), significantly higher than that of a reference using 2,2′,7,7′-tetrakis(N,N-di-p-metoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) as the HTM (14%) as a result of the improved optical transmission through the HTM.

Tripodal Triazatruxene Derivative as a Face-On Oriented Hole-Collecting Monolayer for Efficient and Stable Inverted Perovskite Solar Cells

“…After fabricating perovskite on HCM layers, PL intensity of the perovskite films fabricated on PATAT monolayers was much lower than from the perovskite film on MeO-2PACz (<6% vs 45%) (Figure S36a). The PL lifetime for the pristine perovskite film on quartz was 334 ns and 189 ns for the glass/ITO substrate. It decreased in the HCM/perovskite films to 51, 12, 10, 10, and 8 ns for MeO-2PACz , 3PATAT-C4 , 3PATAT-C3 , 2PATAT-C3 , and 1PATAT-C3 , respectively (Figure S36b).…”

D-A-D Compounds Combining Dithienopyrrole Donors and Acceptors of Increasing Electron-Withdrawing Capability: Synthesis, Spectroscopy, Electropolymerization, and Electrochromism

“… 9 − 13 Their electrical transport properties were also exploited in perovskite-type photovoltaic cells, where they were used as charge carrier transporting materials. 14 − 16 Band gap tuning resulted in the preparation of several narrow-band gap high 17 , 18 and low 19 molecular mass compounds serving as donor components in bulk heterojunction (BHJ) organic photovoltaic cells (OPVs) containing fullerene acceptors. In a different approach, DTP units were used as building blocks of non-fullerene acceptors in the same type of cells.…”

“…This approach led to the elaboration of a plethora of D-A electroactive compounds. − In particular, molecules (macromolecules) containing dithieno­[3,2- b :2′,3′- d ]­pyrrole ( DTP ) or its derivatives , distinguish themselves by exhibiting promising properties in view of their applications in electronics, optoelectronics, and in electrochromic devices. Dithieno­[3,2-b:2′,3′- d ]­pyrrole-based D-A materials were tested as components of active layers in various types of organic field-effect transistors (OFETs). − Their electrical transport properties were also exploited in perovskite-type photovoltaic cells, where they were used as charge carrier transporting materials. − Band gap tuning resulted in the preparation of several narrow-band gap high , and low molecular mass compounds serving as donor components in bulk heterojunction (BHJ) organic photovoltaic cells (OPVs) containing fullerene acceptors. In a different approach, DTP units were used as building blocks of non-fullerene acceptors in the same type of cells. − They were also applied as dyes in dye-sensitized photovoltaic cells. − Several organic light-emitting diodes (OLEDs) were reported, in which compounds containing dithieno­[3,2- b :2′,3′- d ]­pyrrole units served as electroluminophores. − Electrochromic properties of small molecules and high molecular mass compounds containing dithienopyrrole moieties − were also exploited.…”

Rational design of small molecule hole-transporting materials with a linear π-bridge for highly efficient perovskite solar cells

“…However, extended p-conjugation commonly leads to a redshift of the absorption band edge, reducing the transparency. Although some strategies were adopted to avoid the conflict between intrinsic properties, [37][38][39][40][41] the relationship between the molecular structure and photovoltaic performance is not clear enough. In the present work, we have designed a series of linear small molecules as shown in Fig.…”