Science Bulletin：二维D-J CsPbI3太阳能电池的记录效率

Science Bulletin, 2022, 67(13): 1352-1361

https://doi.org/10.1016/j.scib.2022.05.019

Manipulate energy transport via fluorinated spacers towards record-efficiency 2D Dion-Jacobson CsPbI₃ solar cells

氟化间隔阳离子调控能量传输实现二维Dion-Jacobson CsPbI₃太阳能电池的记录效率

雷雨田, 李振华, 王浩旭, 王倩, 彭郭强, 许有奎, 张海华, 王刚, 丁黎明, 靳志文*

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研究背景

       二维CsPbI₃钙钛矿太阳能电池由于出色的稳定性受到了广泛关注, 然而, 二维结构中有机阳离子与无机平面之间复杂的相互作用限制了其光电转换效率的进一步提高. 为此, 兰州大学靳志文团队从功能化有机阳离子的角度出发, 首次将含氟间隔阳离子应用于构筑二维D-J CsPbI₃器件. 相关研究发表在Science Bulletin 2022年第13期.

成果简介

本文首先借助第一性原理计算分析了二维钙钛矿结构中功能化有机阳离子与无机平面的耦合情况, 揭示了含氟有机阳离子能够增加二维结构中的介电常数, 减小激子结合能, 并优化能量传输路径. 

进一步从实验上证明了含氟有机阳离子对增加二维钙钛矿薄膜的结晶度、降低缺陷态密度, 优化载流子的提取与传输等过程具有积极意义. 

基于此, 本文实现了二维D-J CsPbI₃(n=4)器件的记录效率以及良好的运行稳定性. 

本工作从优化二维D-J CsPbI3结构中能量传输路径的角度出发, 思考了器件性能与材料微观结构之间的关系, 为二维CsPbI₃器件性能的进一步发展提供了新的思路.

图文导读

Fig. 1. Organic cations and structure simulation of different 2D D-J CsPbI_3.

(a) Calculated molecular dipole moment of F-PDA²⁺ cation and its electron-density distribution in the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) in comparison to PDA²⁺ cation.

(b) The optimized polyhedron model and its partial enlarged drawing.

(c) The interaction between organic cations as well as organic cations and inorganic plane in the F-PDA-Pb structure.

(d) Definition of equatorial and apical bond lengths and angles of the geometrical structures for 2D D-J CsPbI₃.

(e) A schematic diagram of the interaction between the organic layer and the inorganic octahedron mediating carrier transport.

(f) Charge densities of the VBM in PDA-Pb and F-PDA-Pb.

(g) The band structures and density of states for F-PDA-Pb (n = 2–5), respectively.

Fig. 2. Characterizations of PDA-Pb and F-PDA-Pb film.

(a) FTIR spectrometer spectra; (b) XRD patterns; (c) UV–vis absorption spectra of 2D CsPbI3 (n = 1 and n = 4).

SEM images for F-PDA-Pb film (d₁) and PDA-Pb film (e₁), top-view AFM for F-PDA-Pb film (d₂) and PDA-Pb film (e₂), and surface potential under dark and light condition for F-PDA-Pb film (d₃) and PDA-Pb film (e₃), respectively.

(f) Corresponding mean potential values and (g) X-ray photoelectron spectroscopy spectra of Pb 4f.

Fig. 3.  TA spectra.

Time- and wavelength-dependent TA images, TA spectra at selected probe times and TA spectra of different n phases as a function of delay time for (a, c, e) F-PDA-Pb film and (b, d, f) PDA-Pb film, respectively.

Fig. 4. Photovoltaic performance and stability characterization.

(a) Reverse scan J-V curve.

(b) EQE spectra of the F-PDA-Pb PSCs.

(c) Stabilized power output and current density of the F-PDA-Pb PSCs.

(d) PCE distribution (20 individual devices were collected).

(e) Mott-Schottky curves. 

(f) Stability test of unencapsulated 3D CsPbI₃and 2D D-J CsPbI₃ PSCs in an atmospheric environment with a humidity of 40%. 

(g) Record PCE of 2D D-J/R-P CsPbI₃ (nominal n  5) PSCs relative to reported work.

Fig. 5. Electrical characteristics of F-PDA-Pb and F-PDA-Pb based devices.

(a) Photocurrent density versus effective voltage (J_ph-V_eff) on a double-logarithmic scale. 

(b) The trap state density at room temperature. 

(c) Trap density; (d) dark J-V curves; (e) temperature-dependent conductivity; (f) seminatural logarithmic plots of V_OC versus light intensity.

通讯作者

靳志文

教授，兰州大学。主要研究方向为无机半导体材料、薄膜光电器件。

共同一作

雷雨田

硕士研究生在读，兰州大学。主要研究方向为二维光电材料与器件。

李振华

兰州大学。主要研究方向为强相关耦合系统与材料电子结构的模拟。

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