Sung-Ho Jin

A bulky benzyl-substituted PtON-Benzyl was developed via steric engineering. PtON-Benzyl exhibits deep-blue emission at 453 nm with a FWHM of 28 nm and PLQY of 81.3%. Blue PHOLEDs achieved an EQE of 17.5% and an LT ₅₀ of 36.6 h at 1000 cd m ⁻² .

Pt(II) metal complexes with aggregation‐induced emission (AIE) properties are creating new opportunities in the fields of optoelectronics and their applications. We synthesized a series of AIE‐active sky blue and bluish green Pt(II) complexes with varying structures, such as (Pt1–Pt4). Their photophysical, electrochemical, thermal, and electroluminescence properties were systematically investigated. The suppression of low‐energy excimer emission in (Pt1–Pt4) was confirmed by PL studies of neat films. This is due to the introduction of bulky trityl and diphenyl phosphine oxide Ph ₂ (P═O) in the main ligand and di‐mesityl groups on the ancillary ligand. All the complexes exhibited better photoluminescence quantum yield (PLQYs) in the film state. Consequently, the phosphorescent organic light‐emitting (PHOLED) device with Pt2 as a dopant achieved a maximum current efficiency (CE) of 20 cd/A and a power efficiency (PE) of 14.4 lm/W at a 10 wt% doping ratio, outperforming Pt1 (CE:7.5 cd/A, PE:5.3 lm/W at 15 wt%). Notably, the vacuum deposition PHOLEDs demonstrated significantly superior performance compared to their solution‐processed counterparts. This work provides a foundation for future research into AIE/AIEE‐active emitters for advanced display applications.

Phosphor‐sensitized organic solar cells (PS‐OSCs) enhance exciton utilization and suppress non‐radiative recombination by incorporating triplet‐enabled sensitizers into bulk‐heterojunction blends. Here, we report a green‐emitting Ir‐3 complex as a multifunctional phosphor‐sensitizer in ternary OSCs based on PM6, two newly designed pyrazine‐derived donor polymers, PBDT‐Pyz (N1) and PBDT‐T‐Pyz (N2), and the non‐fullerene acceptor L8‐BO. N1 and N2 exhibit deep HOMO levels (−5.59/−3.63 eV and −5.58/−3.60 eV) and planar backbones for efficient charge transport, while Ir‐3 (E _g ^opt = 2.50 eV, HOMO/LUMO −5.50/−3.0 eV) functions simultaneously as an interfacial compatibilizer, luminescent‐cascade promoter, and triplet‐energy mediator. Strong spin‐orbit coupling in Ir(III) enables near‐quantitative intersystem crossing (ISC), populating long‐lived triplet states that undergo rapid triplet‐triplet energy transfer (TTET) to L8‐BO (Ir‐3 T ₁ = 2.46 eV → L8‐BO T ₁ = 1.85 eV, ΔE _T1 = 0.61 eV), converting otherwise inaccessible triplet excitons into productive charge generation while suppressing non‐radiative voltage loss. The optimized o ‐xylene‐processed PM6:N2:L8‐BO device containing 1 wt.% Ir‐3 achieved a champion PCE of 18.6%, with V _oc of 0.88 V, J _sc of 27.6 mA cm ⁻² , and FF of 76.7%, a 2.6% absolute gain over the binary control. These results establish a combined host‐engineering and phosphor‐sensitization strategy for high‐efficiency, halogen‐free, solvent‐compatible PS‐OSCs.

External single additives have played a key role in achieving high-performance organic solar cells (OSCs) by regulating the active layer morphology. Herein, we added a binary additive (naphthalene + 1-iodonaphthalene) to the PM6:L8-BO active layer. Interestingly, the binary additive simultaneously enhanced current-density (J _sc) and fill factor (FF) to realize state-of-the art power conversion efficiency (PCE) of 18.57%, compared to a pristine device PCE (17.25%). This enhancement in performance is predominantly ascribed to (1) improved photoactive material solubility; (2) balanced mobility; and (3) optimized nanoscale morphology. In addition to the high efficiency of the binary additive-based PM6:L8-BO OSCs, these devices exhibited remarkable long-term stability, retaining up to 97% of their initial performance over 120 days under ambient conditions (temperature at 25 ± 4 °C and humidity: 35–45%). Additionally, we fabricated organic photodetectors (OPDs) containing binary additives. The PM6:L8-BO based OPD produced exhibited excellent quantum efficiency with responsivity and detectivity values of 0.62 A W^{– 1} and 2.10 × 10¹⁰ Jones, respectively. Overall, our work highlights the benefits of utilizing binary additive-based active layers in OSCs and OPDs to produce high performance without compromising long-term device stability.

The development of eco-friendly solution-processed PHOLEDs (s-PHOLEDs) is a significant issue due to the toxicity of halogenated solvents. However, high-performance s-PHOLEDs have predominantly relied on halogenated solvents, owing to their superior ability to dissolve organic materials and facilitate high-quality film formation in the EMLs. To advance the development of eco-friendly s-PHOLEDs, several criteria are required to solve; the development of emitters and host materials having high solubility in eco-friendly solvents and the establishment of optimal conditions for achieving high-quality films, including uniformity, thickness, and morphology. Herein, we developed eco-friendly s-PHOLEDs using a novel green phosphorescent emitter, MECF-pop, and a new thermally cross-linkable hole transport material, C2DPACzPVB, using 2-methylanisole (2-MA) as a food additive solvent for device fabrication. We utilized an exciplex forming mixed hosts system consisting of TCTA as a hole transport type material and TPBi as an electron transport type material. Interestingly, the variation of exciplex formation was observed in the EMLs due to the changed dispersion of TCTA and TPBi according to film-forming conditions. The optimized eco-friendly s-PHOLEDs using chlorobenzene and 2-MA showed maximum external quantum efficiencies of 26.4 and 22.7% and current efficiencies of 94.8 and 81.2 cd A⁻¹, respectively.

The complex molecular structures of electron donor (D)–acceptor (A) polymers provide a wealth of useful hints for producing high power conversion efficiency (PCE) as hole transport materials (HTMs) in perovskite solar cells (PVSCs). Given the recent improvements in PCE, various features are focused on altering the functionalities of HTMs. In this study, a pyrazine‐based acceptor is fused with two known donors benzodithiophene (BDT) and dithienobenzodithiophene (DTBDT) to synthesize two new D–A type polymers (NBD‐Pyz and NDT‐Pyz) to employ them as dopant‐free HTM in PVSCs. The insertion of pyrazine moiety downshifted the energy levels and enhanced coplanarity for both the HTMs. NBD‐Pyz can significantly lower the trap density and passivate the perovskite layer. More interestingly, the NBD‐Pyz HTM performs better than NDT‐Pyz, exhibiting higher hole mobility and better solubility in 2‐methyl anisole (2MA) and o‐xylene. Moreover, a 2MA/o‐xylene cosolvent‐processed dopant‐free polymeric NBD‐Pyz HTM‐based device achieved a champion PCE of 22.9%. Unlike NDT‐Pyz and Spiro‐OMeTAD‐based PVSCs, the unencapsulated NBD‐Pyz devices were more stable, retaining almost 90% of their initial efficiency after 1000 h. In addition, excellent thermal stability was demonstrated by the resulting PVSCs without encapsulation. image