Bezboruah Jasmine, Khator Kanha Ram, Gayen Sayantan, Sanke Devendra Mayurdhwaj, Mahapatra Biplab, Sahoo Anshuman, Nayak Amlandeep, Reddy C Malla, Senanayak Satyaprasad P, Zade Sanjio S
Department of Chemical Sciences and Centre for Advanced Functional Materials, Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur 741246 Nadia West Bengal India
Nanoelectronics and Device Physics Lab, National Institute of Science Education and Research, School of Physical Sciences, OCC of HBNI Jatni 752050 India
Chem Sci. 2024 Oct 17;15(45):19000-12. doi: 10.1039/d4sc04157g.
Understanding the interplay between the molecular structure and material properties of emerging p-type organic semiconductors marks a significant stride in the advancement of molecular electronics. Among the array of promising materials, mechanically flexible single crystals of π-conjugated molecules stand out due to their potential for cutting-edge applications in organic electronics. Notably, derivatives of pyrazinoquinoxaline (PQ) are recognized as versatile building blocks for constructing π-conjugated systems, showcasing good semiconductor performance in organic field-effect transistors (OFETs). In this study, we present an exploration into the p-type charge transport and mechanical characteristics of two newly synthesized PQ derivatives: 5,10-diphenyl-2,3,7,8-tetra(thiophen-2-yl)pyrazino[2,3-g]quinoxaline (DPTTQ) and 2,3,5,7,8,10-hexa(thiophen-2-yl)pyrazino[2,3-g]quinoxaline (HTPQ). HTPQ crystals exhibit flexural behaviour under applied stress, effortlessly returning to their initial configuration upon relaxation. Conversely, two polymorphic forms of DPTTQ crystals display brittle fracture when subjected to a similar stress. Specifically, DPTTQ molecules adopt a β-sheet packing, while HTPQ presents a γ-packing with a corrugated arrangement. Field-effect charge transport measurements reveal p-type charge transport in both DPTTQ and HTPQ, with HTPQ showcasing hole mobility up to 0.01 cm V s, while DPTTQ exhibits mobility that is at least one order of magnitude lower. This variance in the field effect mobility can be directly correlated to the difference in crystal packing, highlighting a clear structure-property correlation. Moreover, taking advantage of the flexural nature of the HTPQ crystals, we fabricated durable electronic devices, which retain their conductivity for over 60 cycles of strain, indicating the efficacy of our chemical design in demonstrating high-performance flexible devices. These findings underscore the promise of semiconducting organics with γ-packing for achieving both better mobility and elasticity for integration into organic electronic devices.
了解新兴p型有机半导体的分子结构与材料特性之间的相互作用，是分子电子学发展中的重要一步。在众多有前景的材料中，π共轭分子的机械柔性单晶因其在有机电子学前沿应用中的潜力而脱颖而出。值得注意的是，吡嗪并喹喔啉（PQ）衍生物被认为是构建π共轭体系的通用结构单元，在有机场效应晶体管（OFET）中展现出良好的半导体性能。在本研究中，我们对两种新合成的PQ衍生物：5,10-二苯基-2,3,7,8-四（噻吩-2-基）吡嗪并[2,3-g]喹喔啉（DPTTQ）和2,3,5,7,8,10-六（噻吩-2-基）吡嗪并[2,3-g]喹喔啉（HTPQ）的p型电荷传输和机械特性进行了探索。HTPQ晶体在施加应力时表现出弯曲行为，松弛后能轻松恢复到初始构型。相反，DPTTQ晶体的两种多晶型在受到类似应力时表现出脆性断裂。具体而言，DPTTQ分子采用β-片层堆积，而HTPQ呈现出具有波纹状排列的γ-堆积。场效应电荷传输测量表明，DPTTQ和HTPQ均表现出p型电荷传输，HTPQ的空穴迁移率高达0.01 cm² V⁻¹ s⁻¹，而DPTTQ的迁移率至少低一个数量级。场效应迁移率的这种差异可直接与晶体堆积的差异相关联，突出了明显的结构-性能相关性。此外，利用HTPQ晶体的弯曲特性，我们制造了耐用的电子器件，该器件在超过60个应变循环中保持其导电性，表明我们的化学设计在展示高性能柔性器件方面的有效性。这些发现强调了具有γ-堆积的半导体有机物在实现更好的迁移率和弹性以集成到有机电子器件方面的前景。
