全无机钙钛矿量子点发光二极管的制备与性质研究

Novel and all-inorganic perovskite quantum dots-LEDs can be fabricated by all-solution processes via using P-type NiO as the hole transportation layer, N-type ZnO as the electron transportation layer, and CsPbX3(X=Cl, Br, I) quantum dots as the emitting layer. Compared with traditional Cd-based quantum dot-LEDs, the advantages of this project are as follows: 1. the toxicity of Pb-based perovskite is relatively low since the toxicity of Pb is only 1/10 of that of Cd; 2. the synthesis of Pb-based perovskite quantum dots is more facile, which can be conducted in the open air at room temperature for only 10 s; thus multi-grams-scale preparation can be easily realized; 3. for high-performance Cd-based quantum dots-LED in the literature, organic hole transportation and inorganic ZnO electron transportation layer were adopted, which lead to unmatched carrier transportation and an extremely high hole injection barrier. Compared with Cd-based quantum dots, the valence band position of Pb-based perovskite quantum dots is enhanced by 1 eV; thus traditional P-type NiO can be used a hole transportation layer for Pb-based perovskite LEDs, which enable us to fabricate all-inorganic perovskite quantum dots-LEDs.

我们以P型NiO为空穴传输层、N型ZnO为电子传输层、CsPbX3(X=Cl, Br, I)钙钛矿量子点为发光层，通过全溶液方法制备出新颖的全无机钙钛矿量子点发光二极管器件。与传统的镉基量子点发光二极管相比，我们制备的全无机钙钛矿量子点发光二极管具有如下特色和优点：1. 铅的毒性仅为镉的1/10，因此我们制备的铅基钙钛矿量子点发光二极管毒性较低；2. 铅基钙钛矿量子点的制备更加简单，整个制备过程在室温下空气中仅需要10秒钟就能完成，并且容易实现多克级的宏量制备; 3. 文献中高效率的镉基量子点发光二极管均采用有机空穴传输层加无机ZnO电子传输层的方式，两者之间存在迁移率不匹配以及空穴注入势垒过高的难题，对于铅基的钙钛矿量子点，其价带位置与相应的镉基量子点相比大约上升了1 eV，因此传统的P型NiO可以作为铅基钙钛矿量子点发光二极管的空穴传输层，从而能够制备出全无机的钙钛矿量子点发光二极管。

钙钛矿发光量子点由于其发光效率高、发光颜色整个可见光区可调、发光谱窄等优点在电致发光二极管中具有非常重大的应用前景。然而钙钛矿发光量子点稳定性差的缺点制约了他们的应用。在本项目中，我们采用无机的空穴传输层和无机的电子传输层，结合钙钛矿量子点发光层，制备一种全无机的钙钛矿量子点发光二极管，拟提高电致发光器件的稳定性。经过四年的努力，我们实现了在室温下空气中制备了高发光的CH3NH3PbX3和CsPbX3 (X=Cl, Br, I)钙钛矿纳米晶，所制备的钙钛矿纳米晶的荧光发光量子产率、发光光谱范围、荧光峰半高宽等指标均达到本项目预期的目标。此外，我们通过溶液成膜的方法也制备了多种高质量的无机空穴传输层和无机电子传输层薄膜，包括MoO3、NiO、V2O5、ZnO和SnO2等无机传输层薄膜，并且我们利用钙钛矿半导体作为发光层、采用无机电子传输层和无机空穴传输层组装器件，我们也成功制备了全无机的钙钛矿量子点发光二极管和全无机的钙钛矿太阳能电池。研究结果表明全无机的器件除了稳定性比有机/无机杂化传输层的器件高以外，全无机器件的电流效率、流明效率和外量子效率均不理想。究其原因主要还是p型无机传输层制备困难造成的。总之，在项目执行期间我们一共发表了与该项目密切相关的研究论文14篇，包括2篇ACS Appl. Mater. Interfaces、1篇Langmuir、2篇J. Mater. Chem. C、1篇Inorg. Chem.、1篇J. Power Sources、4篇Mater. Res. Express、1篇Optical Materials、2篇Journal of Luminescence。