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Abstract：
Two-dimensional (2D) hybrid organic/inorganic perovskites are an emerging materials class for optoelectronic and spintronic applications due to strong excitonic absorption and emission, large spin-orbit coupling, and Rashba spin-splitting effects. For many of the envisioned applications, tuning the majority charge carrier (electron or hole) concentration is desirable, but electronic doping of metal-halide perovskites has proven to be challenging. Here, we demonstrate electron injection into the lower-energy branch of the Rashba-split conduction band of 2D phenethylammonium lead iodide by means of n-type molecular doping at room temperature. The molecular dopant, benzyl viologen (BV), is shown to compensate adventitious p-type impurities and can lead to a tunable Fermi level above the conduction band minimum and increased conductivity in intrinsic samples. The doping-induced carrier concentration is monitored by the observation of free-carrier absorption and intraband optical transitions in the infrared spectral range. These optical measurements allow for an estimation of the Rashba splitting energy ER ≈38 ± 4 meV. Photoinduced quantum beating measurements demonstrate that the excess electron density reduces the electron spin g-factor by ca. 6%. This work demonstrates controllable carrier concentrations in hybrid organic/inorganic perovskites and yields potential for room temperature spin control through the Rashba effect.
摘要：
由于强烈的激子吸收和发射，二维（2D）混合有机/无机钙钛矿是用于光电和自旋电子应用的新兴材料类别。大自旋-轨道耦合，和Rashba旋转分裂效果。对于许多预想的应用，调谐多数电荷载流子（电子或空穴）浓度是可取的，但事实证明，金属卤化物钙钛矿的电子掺杂具有挑战性。这里,我们证明了在室温下通过n型分子掺杂将电子注入2D苯乙基铵碘化铅的Rashba分裂导带的较低能量分支。分子掺杂剂，苄基紫精（BV），显示可补偿不定的p型杂质，并可导致高于导带最小值的可调费米能级，并增加本征样品的电导率。通过观察红外光谱范围内的自由载流子吸收和带内光学跃迁来监测掺杂引起的载流子浓度。这些光学测量允许估计Rashba分裂能量ER≈38±4meV。光诱导的量子跳动测量表明，过量的电子密度使电子自旋g因子降低了约。6%。这项工作证明了杂化有机/无机钙钛矿中可控的载流子浓度，并通过Rashba效应产生了室温自旋控制的潜力。
