THz EPR-on-a-Chip for Enhanced Spin Sensitivity

电子顺磁共振（EPR）是化学、物理、医学和材料科学中最强大的分析方法之一。它利用自由基电子自旋作为探针来解决复杂材料和界面的结构-功能关系。不幸的是，EPR的广泛的应用潜力是由非常高的仪器成本，中等灵敏度，并在样品环境中的灵活性不足，由于常规使用的谐振器为基础的测量原理抵消。拟议的项目旨在通过扩展最近推出的芯片上EPR（EPRoC）方法来克服EPR的上述限制，该方法将整个自旋激发源和检测器集成到单个集成电路上，从GHz到THz范围。总的来说，该项目将产生的新THz EPRoC光谱仪将大大降低THz EPR的实验复杂性，同时提供前所未有的灵敏度和光谱分辨率，比GHz EPRoC至少高出两个数量级。为此，我们将在理论上和实验上研究一类新的压控振荡器（VCO），利用分裂电感作为太赫兹磁场源和EPR探测器。在该项目中，我们将应用这种新的THz技术来研究位于具有非晶硅选择性接触层的高效晶体硅单结和串联钙钛矿太阳能电池的界面区域中的缺陷。在这里，我们将通过检测太阳能电池电流中的顺磁缺陷作为磁性指纹，在环境操作条件下和液氦温度下，实现前所未有的灵敏度，只有几百个缺陷。该项目将展示THz EPR光谱的巨大应用潜力，并将有助于为THz EPR光谱在材料科学，分析化学和生物医学研究中的广泛应用铺平技术道路。

Electron paramagnetic resonance (EPR) is amongst the most powerful analysis methods in chemistry, physics, medicine, and materials science. It utilizes radical electron spins as probes to resolve the structure-function relationship of complex materials and interfaces. Unfortunately, EPR’s broad application potential is offset by very high instrumentation costs, moderate sensitivity, and insufficient flexibility in the sample environment due to the conventionally used resonator-based measurement principle. The proposed project aims at overcoming the aforementioned limitations of EPR by extending the recently introduced EPR-on-a-chip (EPRoC) approach, which integrates the entire spin excitation source and detector onto a single integrated circuit, from the GHz into the THz regime. Overall, the new THz EPRoC spectrometer that will emerge from the project will greatly reduce the experimental complexity of THz EPR and, at the same time, provide unprecedented sensitivity and spectral resolution, being at least two orders of magnitude better than GHz EPRoC. To this end, we will both theoretically research and experimentally investigate a new class of voltage-controlled oscillators (VCOs) that make use of split inductors as THz magnetic field sources and EPR detectors. Within the project, we will apply this new THz technology to study defects located in the interface region of the high-efficiency crystalline silicon single junction and tandem perovskite solar cells with an amorphous silicon selective contact layer. Here, we will achieve an unprecedented sensitivity of only a few hundred defects by detecting the paramagnetic defects as a magnetic fingerprint in the solar cell’s current, both under ambient operating conditions and at liquid helium temperatures. The project will demonstrate the immense application potential of THz EPRoC spectroscopy and will help to pave the technological road for a broad application of THz EPR spectroscopy in materials science, analytical chemistry, and biomedical research.