香港城市大学Alex Jen团队连续两篇Angew！有机太阳能电池大突破！

1.通过引入稠环分子内给体-受体相互作用设计本征稳定的空穴选择性自组装单分子层

引入给体共轭单元作为头部功能基团的空穴选择性自组装单分子层（SAM）在实现高性能有机太阳能电池（OSC）方面取得了显著成功。然而，这些分子的最低未占分子轨道（LUMO）较浅，往往导致其在光照后处于不稳定高能状态，因此易发生光降解。为了解决这个问题，香港城市大学Alex Jen团队首次在SAM分子的设计中引入了稠环分子内给体-受体（D-A）相互作用得到了新型SAM分子JJ32，以大幅降低LUMO能级，提升分子本征稳定性。

JJ32表现出显著增强的光稳定性和分子间相互作用。此外，稠环分子内D-A相互作用还有助于稳定JJ32的阳离子自由基态，从而显著提升了氧化还原稳定性。这使得JJ32更适配与多酸（POM）结合构筑复合空穴选择性层（HSL），基于JJ32-POM复合HSL的OSC器件实现了19.85%的PCE，同时显著增强了稳定性。这项研究不仅提出和验证了引入稠环分子内D-A相互作用设计高性能SAM的分子设计原理，而且阐明了SAM结构与POM掺杂行为之间的关系，为设计用于高性能OSC的本征稳定的SAM分子提供了全新的分子设计策略。

Figure 1. a) Chemical structures and modification principles of 2PACz and JJ32; b) The frontier orbital distribution of 2PACz and JJ32 and the HOMO-LUMO energy levels obtained by DFT calculation; c) ESP distributions of 2PACz and JJ32, where the ESP minimum points are marked by yellow dots.

Figure 2.The molecular packing patterns in single crystals corresponding to the π-scaffolds of a-e) JJ32 (12H-benzo[5,6][1,4]thiazino[2,3-b]quinoxaline) and f) carbazole.

Figure 3.Proposed oxidation of 2PACz (a, b) and JJ32 (c, d) by HPWO to form radical cation and their subsequent potential decomposition mechanisms;e) Absorption spectra of dichloromethane solutions of phosphonate precursors of 2PACz and JJ32 before and after mixing with HPWO; f) Absorption spectra of films of 2PACz and JJ32 before and after mixing with HPWO; g)ESR spectra of solid powders of 2PACz, JJ32 and their mixtures with HPWO; h) The energy level diagram of ITO, different HSL and polymer donor materials (D18) in OSCs.

Figure 4.a) Device architecture of the OSCs; b) J-Vcurves for OSC devices based on LBL architecture comprising different HSLs; c) EQE spectra for devices comprising different HSLs; d) J−V curves for OSC devices with BHJ architecture (D18:L8-BO:DYO-IT) based on JJ32/HPWO HSL, where HPWO was coated at different concentrations in methanol. e) MPP tracking for devices comprising different HSLs under continuous one-sun illumination.

Wenlin Jiang, Baobing Fan*, Lingchen Kong, Ze-Fan Yao, Wansong Shang, Chun-To Wong, Francis R. Lin, Alex K.-Y. Jen*; Design of Intrinsically Stable Hole-Selective Self-Assembled Monolayers by Introducing Fused-ring Intramolecular Donor-Acceptor Interactions, Angew. Chem. Int. Ed.2025, e202507273；DOI: 10.1002/anie.202507273

2.区域特异性卤化调节自组装单层中的分子偶极子用于高性能有机太阳能电池

卤化咔唑衍生的自组装单分子层（SAM）是有机太阳能电池（OSC）中极具前景的空穴提取材料。虽然卤化被认为能够有助于优化SAM的分子偶极、分子间相互作用和能级对齐，但高度极化的碳卤键可能具有稳定性隐患，并且根据其区域化学性质，容易发生光裂解反应。鉴于此，香港港城市大学Alex Jen团队通过溴化具有更强偶极子的螺旋状7H-二苯并[c,g]咔唑基SAM（CbzNaph），研究了溴化对SAM分子的区域化学特异性影响，包括本征稳定性、静电势分布和分子偶极子的变化。发现：并非引入卤素就能提升分子偶极、并非引入卤素就会降低光稳定性，这与卤化位点直接相关。此外，还建立了SAM本征分子稳定性与SAM修饰衬底的表面物性稳定性之间的相关性，并与OSC的性能和稳定性相关联。

按照以上分子设计原理在CbzNaph的化学惰性位点进行溴化得到的SAM分子JJ26具有显著提升的分子偶极子，同时保持了优异的本征稳定性。此外，JJ26分子间相互作用和结晶性协同增强，促进了SAM致密组装，有效调节了ITO的功函数，增强了SAM在外部应力下的稳定性。因此，基于JJ26的OSC表现出显著的性能提升，效率达到19.35%，同时稳定性也显著增强。这项研究表明，精确调控SAM分子的区域化学结构对于提高分子本征性质和器件性能至关重要。

Figure 1.Schematic illustration of the interface of ITO modified by the SAMs with a positive dipole (for this orientation, the molecule's negative charge must be positioned upward and the positive charge backward, like the structure of conjugated skeletons such as the carbazole core) and the energetic alignment considerations in OSCs.

Figure 2.(a)JJ25 and JJ26 obtained by regiospecific bromination of CbzNaph, (b) CV characterized oxidation potential of phosphates corresponding to CbzNaph, JJ25, and JJ26 in CH2Cl2, Ferrocene was used as external reference, and the potentials were presented by reference to E1/2(Fc/Fc+). (c) The ESP maps of CbzNaph, JJ25 and JJ26. The ESP minimum point on the carbazole skeleton is marked by a yellow dot.

Figure 3. The molecular packing patterns in the crystal lattice of JJ26.(CCDC No.: 2408036)

Figure 4. a) UPS spectra of CbzNaph-, JJ25- and JJ26-covered ITO. b) The energy level diagram of ITO, different hole extraction layers (HEL) and active layer materials in OSCs.(c) KPFM images and (d) contact potential difference statistical distribution of CbzNaph-, JJ25- and JJ26-covered ITObefore and after aging.

Figure 5.a) Dark current through a hole-only device based on CbzNaph, JJ25, and JJ26 HEL. (b) J–V characteristics and (c) EQE spectrafor PM6/BTP-eC9-based devices using CbzNaph-, JJ25 and JJ26-HEL. (d) J–V characteristicsfor D18:L8BO:Y6-OBO based devices using CbzNaph-, JJ25 and JJ26-HEL. e) Mott-Schottky plots for devices comprising different HELs. f) Photostability of D18/L8-BO:Y6-OBO-based devices using JJ25- and JJ26-modified substrates.

Wenlin Jiang+, Yanxun Li+, Huanhuan Gao,* Lingchen Kong, Chun-To Wong, Xi Yang, Francis R. Lin, and Alex K.-Y. Jen*, Regiospecific Halogenation Modulates Molecular Dipoles in Self-Assembled Monolayers for High-Performance Organic Solar Cells, Angew. Chem. Int. Ed. 2025, e202502215, DOI: 10.1002/anie.202502215

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