Molecular doping of organic semiconductors and beyond: resolving fundamental processes and increasing doping efficiency

有机半导体及其他分子掺杂：解决基本过程并提高掺杂效率

• 批准号: RGPIN-2018-05092
• 负责人: Salzmann, Ingo
• 金额: $ 2.48万
• 依托单位: Concordia University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=664172
• 关键词: Molecular; doping; organic; semiconductors; beyond

Doping inorganic semiconductors such as crystalline silicon by introducing impurities is the basis of all transistor technology, which enables the functionality of today's electronic devices. In the past decades, organic semiconductors emerged as fascinating alternative to inorganics promising large-area processability on flexible-substrates and enormous versatility, as their opto-electronic properties, their bandgap in particular, can be tuned by their chemical structure. The concept of doping has only recently been adapted for organics by employing molecular dopants, where all novel display technology based on organic light emitting diodes (OLEDs) today uses doped conjugated materials. Despite enormous success in applications, however, the fundamental processes of doping are still poorly understood for organic semiconductors and material design remains largely empirical. In previous work, we identified the chemical interaction between semiconductor and dopant as key factor for their low doping efficiency, as, rather than ion pairs, charge transfer complexes tend to form and take over the role of the dopants, however, of significantly reduced strength.******In the present multidisciplinary research program, we aim to, first, exploit this novel understanding for regaining dopant strength by modifying the mechanism of intermolecular coupling. We will employ semiconductors capable of interacting with more than one dopant, which will make effective acceptor levels energetically more accessible. Alternatively, as charge-transfer complex formation is due to the coupling, we will inhibit the coupling by employing species of sterically shielded functional cores. Second, as we found that complex formation only occurs for molecular semiconductors, while conjugated polymers indeed form ion pairs upon doping, we aim to derive a unifying picture valid for both, from which their different doping behavior emerges naturally. To this end, we will increase the number of repeat units from the oligo- to the polymer limit, thereby assess the role of interaction locality, and observe the transition between the seemingly incongruous doping phenomenologies. Third, we aim to augment molecular doping by chemical selectivity through using Lewis acids as p-dopants, where charge transfer is restricted to species capable of acting as Lewis base. Finally, we will go beyond traditional doping to gain spatial control over the charge density in buried layers. Instead of dopant admixture, tailored energy-level alignment will render layers p-/n-doped via energy level pinning with the substrate. ******Overall, the proposed program will establish a complete picture of doping in organic semiconductors. It will enable knowledge-based chemical design for controlling charge density just as precisely as we customarily do today with inorganic semiconductors, for ultimately approaching similar functionality.

通过引入杂质的兴奋剂无机半导体，例如结晶硅，是所有晶体管技术的基础，它可以实现当今电子设备的功能。在过去的几十年中，有机半导体成为无机替代品的替代品，有望在柔性材料和巨大的多功能性上进行大面积的加工性，因为它们的光电电特性（尤其是它们的带隙）可以通过其化学结构来调节。兴奋剂的概念直到最近才通过使用分子掺杂剂来改编成有机物，那里的所有新型展示技术基于有机光发射二极管（OLEDS）今天使用掺杂的共轭材料。尽管在应用方面取得了巨大的成功，但是对于有机半导体和材料设计仍未对掺杂的基本过程仍然很少。在先前的工作中，我们确定了半导体和掺杂剂之间的化学相互作用是其低掺杂效率的关键因素，因为，而不是离子对，电荷转移络合物倾向于形成并接管掺杂剂的作用，但是，在本新型研究计划中，我们旨在改善Dopant的实力，以显着降低强度。耦合。我们将采用能够与多个掺杂剂进行交互的半导体，这将使有效的受体水平在能量上更容易获得。另外，由于电荷转移复合物的形成是由于耦合而引起的，因此我们将通过采用固有屏蔽功能核的物种来抑制耦合。其次，正如我们发现复合物形成仅对分子半导体发生，而掺杂时的共轭聚合物确实形成了离子对，我们的目的是从两者中得出有效的统一图片，它们的不同掺杂行为自然而然地出现。为此，我们将增加从寡聚量极限到聚合物极限的重复单位数量，从而评估相互作用位置的作用，并观察到看似不协调的兴奋剂现象学之间的过渡。第三，我们的目的是通过使用刘易斯酸作为p-掺杂剂来增强化学选择性的分子掺杂，在这种情况下，电荷转移仅限于能够充当刘易斯碱的物种。最后，我们将超越传统的兴奋剂，以获得对埋藏层的充电密度的空间控制。定制的能量级比对代替掺杂剂混合物，将通过用基板固定的能级固定层p-/n掺杂层。 ******总的来说，拟议的计划将建立有机半导体中掺杂的完整图片。它将启用基于知识的化学设计，以控制电荷密度，就像我们今天使用无机半导体一样，最终接近类似的功能。