Enhanced Charge Transfer and Responsivity in Hybrid Quantum Dot/Graphene Photodetectors Using ZnO as Intermediate Electron‐Collecting Layer,Advanced Electronic Materials

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Enhanced Charge Transfer and Responsivity in Hybrid Quantum Dot/Graphene Photodetectors Using ZnO as Intermediate Electron‐Collecting Layer
Advanced Electronic Materials ( IF 5.3 ) Pub Date : 2020-05-11 , DOI: 10.1002/aelm.202000014
Seungbae Ahn ₁ , Wenjun Chen ₁ , Miguel A. Moreno‐Gonzalez ₁ , Malcolm Lockett ₁ , Jiaying Wang ₁ , Oscar Vazquez‐Mena ₁

Affiliation

Hybrid graphene (Gr)–quantum dot (QD) photodetectors have shown ultrahigh photoresponsivity combining the strong light absorption of QDs with the high mobility of Gr. QDs absorb light and generate photocarriers that are efficiently transported by Gr. Typically, hybrid PbS–QD/graphene photodetectors operate by transferring photogenerated holes from the QDs to Gr while photoelectrons stay in the QDs inducing a photogating mechanism that achieves a responsivity of 6 × 10⁷ A W⁻¹. However, despite such high gain, these systems have poor charge collection with quantum efficiency below 25%. Herein, a ZnO intermediate layer (PbS‐QD/ZnO/Gr) is introduced to improve charge collection by forming an effective p‐n PbS‐ZnO junction driving the electrons to the ZnO layer and then to Gr. This improves the photoresponsivity of the devices by nearly an order of magnitude with respect to devices without ZnO. Charge transfer to Gr is demonstrated by monitoring the change in Fermi level under illumination for conventional PbS‐QD/Gr and for ZnO intermediate PbS‐QD/ZnO/Gr devices. These results improve the capabilities of hybrid QD/Gr configurations for optoelectronic devices.

中文翻译：

使用ZnO作为中间电子收集层的混合量子点/石墨烯光电探测器中增强的电荷转移和响应性

混合石墨烯（Gr）-量子点（QD）光电探测器显示出超高的光响应性，将QD的强光吸收与Gr的高迁移率结合在一起。QD吸收光并生成可被Gr有效传输的光载流子。通常，混合的PbS–QD /石墨烯光电探测器通过将光生空穴从QD转移到Gr来工作，同时光电子停留在QD中，从而诱导实现6×10 ⁷ AW ^-1响应度的光闸机制。然而，尽管增益如此之高，但这些系统的电荷收集却很差，量子效率低于25％。在此，引入了ZnO中间层（PbS-QD / ZnO / Gr），通过形成有效的p-n PbS-ZnO结来驱动电子到ZnO层，然后到达Gr，从而改善电荷收集。相对于没有ZnO的器件，这将器件的光响应性提高了近一个数量级。通过监控常规PbS-QD / Gr和ZnO中间PbS-QD / ZnO / Gr器件在照明下费米能级的变化，可以证明电荷向Gr的转移。这些结果提高了光电设备混合QD / Gr配置的功能。

更新日期：2020-05-11

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