Zhao Yuanyuan, Zhu Jingwei, He Benlin, Tang Qunwei
College of Mechanical and Electronic Engineering, Shandong University of Science and Technology, Qingdao 266510, PR China.
School of Materials Science and Engineering, Ocean University of China, Qingdao 266100, PR China.
ACS Appl Mater Interfaces. 2021 Mar 10;13(9):11058-11066. doi: 10.1021/acsami.0c22542. Epub 2021 Feb 26.
The all-inorganic cesium lead bromide (CsPbBr) perovskite solar cells (PSCs) have attracted considerable interest because of their outstanding environmental stability and low manufacturing cost. However, the state-of-the-art mesoscopic titanium dioxide (TiO) electron-transporting layers (ETLs) always present low electron mobility, are destructive to perovskites under ultraviolet light illumination, as well as possess high sintering temperature. Nanostructured tin dioxide (SnO) is a promising electron-transporting material for high-efficiency PSCs due to matching energy-level alignment with the perovskite layer, improved optical transparency, high electron mobility, excellent photostability, and low-temperature processing. Furthermore, rapid but poorly controlled perovskite crystallization makes it difficult to scale up planar PSCs for industrial applications. To address this issue, we adopt a dimensional SnO ETL to change the surface wettability for uniform perovskite coverage over large areas and the growth of large-sized CsPbBr grains, resulting in a maximum grain size of 1.65 μm. Moreover, the dimensional SnO ETL could increase the interfacial contact area between the CsPbBr layer and the ETL and enhance the electronic contact for efficient electron extraction to suppress or to eliminate the notorious hysteresis behavior. As expected, a power conversion efficiency (PCE) of 9.51% with an almost hysteresis-free phenomenon is achieved through dimensionality control of SnO films attributed to the remarkably enhanced light harvesting, accelerated electron extraction, diminished defect density, and reduced charge recombination. Upon further interfacial modification with graphene quantum dots (GQDs), the PSC based on the two-dimensional SnO ETL achieves a champion PCE of 10.34% due to the improved energy-level alignment at the device interface. Moreover, the best all-inorganic CsPbBr PSC free of encapsulation retains 93% of initial efficiency over 10 days at 80% relative humidity. This work provides an effective dimensionality control strategy for optimized charge transportation and enlarged perovskite grain size to make stable and efficient all-inorganic CsPbBr PSCs.
全无机铯铅溴化物（CsPbBr）钙钛矿太阳能电池（PSC）因其出色的环境稳定性和较低的制造成本而备受关注。然而，目前最先进的介观二氧化钛（TiO）电子传输层（ETL）总是呈现出低电子迁移率，在紫外光照射下对钙钛矿具有破坏性，并且烧结温度高。纳米结构的二氧化锡（SnO）由于与钙钛矿层的能级匹配、改善的光学透明度、高电子迁移率、优异的光稳定性和低温处理，是用于高效PSC的一种有前途的电子传输材料。此外，钙钛矿快速但难以控制的结晶使得难以扩大平面PSC以用于工业应用。为了解决这个问题，我们采用一维SnO ETL来改变表面润湿性，以在大面积上实现均匀的钙钛矿覆盖以及大尺寸CsPbBr晶粒的生长，从而得到最大晶粒尺寸为1.65μm。此外，一维SnO ETL可以增加CsPbBr层与ETL之间的界面接触面积，并增强电子接触以实现高效的电子提取，从而抑制或消除臭名昭著的滞后行为。正如预期的那样，通过对SnO薄膜进行维度控制，实现了9.51%的功率转换效率（PCE），几乎没有滞后现象，这归因于显著增强的光捕获、加速的电子提取、降低的缺陷密度和减少的电荷复合。在用石墨烯量子点（GQD）进行进一步的界面修饰后，基于二维SnO ETL的PSC由于器件界面处能级排列的改善，实现了10.34%的最佳PCE。此外，在80%相对湿度下，最佳的无封装全无机CsPbBr PSC在10天内保持了93%的初始效率。这项工作为优化电荷传输和扩大钙钛矿晶粒尺寸提供了一种有效的维度控制策略，以制造稳定且高效的全无机CsPbBr PSC。
