Zhenhu Zhang

Selective precursor coordination enables homogeneous prenucleation clusters, uniform crystallization, and efficient, outdoor-stable perovskite photovoltaics.

SO ₂ , owing to its serious health and environmental risks, has driven the development of highly efficient materials for its capture and sequestration.

Inefficient hole injection poses a major challenge in the realization of stable and economically feasible solution-processed blue quantum dot light-emitting diodes (QLEDs). The advancement of hole transport materials (HTMs) for the realization of high-performance blue QLEDs has demonstrated considerable challenges, primarily attributed to their intrinsic low hole mobility and mismatched energy levels. Herein, two vinyl-based cross-linkable HTMs, 4,4′-bis(3-vinyl-9H-carbazol-9-yl)-1,1′biphenyl (CBP-V) and 2,8-bis(3-vinyl-9H-carbazol-9-yl)dibenzo[b,d]thiophene (KSP-V), are designed and synthesized. Compared with CBP-V, KSP-V possesses a relatively low cross-linking temperature of 190 °C with a nearly 100% solvent resistance. Moreover, KSP-V exhibits exceptional hole transport properties, with a notable 4.2-fold enhancement in hole mobility. By substituting thiophene groups for biphenyl groups, the highest occupied molecular orbital level of KSP is reduced to −5.92 eV. When applying KSP to solution-processed blue QLEDs [Commission Internationale de l'Eclairage coordinates of (0.15, 0.03)], the devices exhibit excellent properties. Particularly, the maximum luminance of 27 036 cd m−2 and external quantum efficiency of 15.69%. Our work provides important guidance for the rational design of cross-linkable HTMs for solution-processed blue QLEDs.

Quantum dot light emitting diodes (QLEDs) have become a promising technology for next generation displays due to their outstanding photometric performance. Cross-linked hole transport materials (HTMs) have attracted wide attention in the field of QLED because of their high thermal stability and excellent solvent resistance. However, the low carrier mobility of cross-linked HTM hinders the charge injection balance of blue QLEDs, preventing their efficiency from meeting the requirements for full-color display applications. Here, to improve the carrier transport performance of cross-linked HTMs, dibenzothiophene with a large conjugated structure was selected as the central structure to develop a cross-linked HTM (V-KSP). Compared with the reported V-CBP, V-KSP with the central conjugate structure shows lower effective mass of electrons and holes, which significantly improves the carrier mobility of V-KSP by two orders of magnitude, from 6.54 × 10−5 to 2.72 × 10−3 cm2 V−1 s−1. Benefiting from the remarkable improvement of charge transport properties, the external quantum efficiency (EQE) of blue QLED with V-KSP reaches 15.6%, with the deep blue emission of Commission International de I'Eclaialia (0.15, 0.03), which will be significantly higher than that of blue QLED with V-CBP (EQE = 11.5%). These results provide not only theoretical guidance for designing high-performance cross-linked HTMs but also more choices for fabricating high-performance blue QLED.

Perovskite solar cells (PSCs) with dopant-free hole transporting layers (HTLs) have attracted wide attention owing to their excellent photoelectric conversion efficiency and environmental stability. However, the hole transporting materials (HTMs) used to prepare dopant-free HTLs seriously hinder the commercial development of PSCs because of their high production cost and complicated preparation process. Herein, we chose thiophene as the central core to synthesize two low-cost HTMs, namely S1 and S2. Owing to the introduction of the ethylene bridge, the conjugated structure of S2 was expanded, and the steric hindrance of triphenylamine was reduced, which endowed S2 with a higher carrier mobility of 1.83 × 10⁻⁴ cm² V⁻¹ s⁻¹ than that of S1 with 6.3 × 10⁻⁵ cm² V⁻¹ s⁻¹. Furthermore, the S2-based PSCs provided an excellent power conversion efficiency of 20.13%, which was higher than those of PSCs based on S1 (18.01%). Besides, PSC devices with S1 and S2 as dopant-free HTL maintained more than 85% of their initial efficiency in air for 60 days. This work not only enriches the material system of dopant-free HTMs but also provides a simple and effective strategy for the preparation of low-cost and high-performance HTMs, paving the way for the commercialization of PSCs with dopant-free HTLs.

Benefiting from the expansion of the central structure, the carrier mobility of HTMs is elevated to 2.56 × 10 ⁻⁴ cm ² V ⁻¹ s ⁻¹ . Thus, the PCE of PSCs with dopant-free HTL is increased from 17.57% to 20.37%.