Optimizing the Back Contact of Kesterites and Perovskites: Band Edge Design and Defect Engineering in Molybdenum Chalcogenides
Optimizing the Back Contact of Kesterites and Perovskites: Band Edge Design and Defect Engineering in Molybdenum Chalcogenides
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DOI：
10.1002/adsu.202100457
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发表时间：
2022-01
影响因子：
7.1
通讯作者：
Huiwen Xiang;Jinping Zhang;Hanzhen Liang;Ruizhen Zhu;Chengyan Liu;Yu Jia
中科院分区：
文献类型：
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作者：
Huiwen Xiang;Jinping Zhang;Hanzhen Liang;Ruizhen Zhu;Chengyan Liu;Yu Jia
背接触作为太阳能电池器件的重要组成部分，在有效分离载流子和减少界面复合方面起着至关重要的作用。通过对背接触的界面能带排列、厚度和缺陷特性的分析，提出了一种背接触的设计原则，使背接触能同时兼顾短路电流(JSC)、开路电压(VOC)、串联电阻(Rs)和非辐射复合中心(NRCS)等相关因素。优选的背接触应具有(I)高价带最大值(VBM)和(Ii)相对于吸收体低的费米能级，以驱动空穴提取和阻止电子泄漏，(Iii)在p+型特性的前提下进行薄设计，以有效地减少Rs，这也确保在吸收体侧有一个宽的耗尽区来促进空穴收集，以及(Iv)没有额外的深能级缺陷作为界面NRCS。以硫族钼为例，Vb族元素掺杂实现的p+型MoSe_2/MoS_2满足设计原则，有望作为钙钛矿/钾钛矿太阳电池的背接触材料。这项研究为设计理想的背接触提供了理论指导，并展示了如何通过界面优化来提高太阳能电池的光伏性能。
Back contacts, as an important part of solar cell devices, play a critical role in efficient separation of carriers and reduction of interfacial recombination. Here, by analyzing interfacial band alignment, thickness and defect properties of back contacts, a design principle for back contacts is proposed to properly accommodate the interrelated factors of short‐circuit current (Jsc), open‐circuit voltage (Voc), series resistance (Rs), and nonradiative recombination centers (NRCs) at the same time. A preferred back contact should have (i) a high valance band maximum (VBM) and (ii) a low Fermi level relative to absorber to drive hole extraction and block electron leakage, (iii) a thin design under the premise of p+‐type characteristic to effectively reduce Rs, which also ensures a wide depletion region on the absorber side to promote hole collection, and (iv) no additional deep‐level defects as interfacial NRCs. Taking molybdenum chalcogenide as example, p+‐type MoSe2/MoS2 realized by group VB element doping satisfies the design principles and is promising as an excellent back contact for kesterite/perovskite solar cells. This study gives theoretical guidance for designing an ideal back contact and shows how to improve the photovoltaic performance of solar cells by interfacial optimization.