Qi Yafang, Liu Yao, Kou Dongxing, Zhou Wenhui, Zhou Zhengji, Tian Qingwen, Yuan Shengjie, Meng Yuena, Wu Sixin
The Key Laboratory for Special Functional Materials of MOE, Collaborative Innovation Center of Nano Functional Materials and Applications, Henan University, Kaifeng, Henan 475004, China.
ACS Appl Mater Interfaces. 2020 Mar 25;12(12):14213-14223. doi: 10.1021/acsami.0c02629. Epub 2020 Mar 13.
Material crystallinity is the overriding factor in the determination of the photoelectric properties of absorber materials and the overall performance of the photovoltaic device. Nevertheless, in the CuZnSn(S,Se) (CZTSSe) photovoltaic device, the bilayer or trilayer structure for the absorber has been broadly observed, which is generally harmful to the cell performance because the probability of photogenerated carrier recombination at grain boundaries significantly increased. Herein, our experiment reveals that the application of anions to a new family of (Cu,Ag)ZnSn(S,Se) (CAZTSSe) materials leads to an increase in grain size and crystallinity. It is inspiring that using acetate starting materials in the precursor solution, a uniform, compact, and pinhole-free CAZTS precursor film was obtained, and the smoothness of the films surpassed that of films fabricated from the oxide route. More importantly, the crystallization of the CAZTSSe film has been considerably enhanced after selenization, and large grains going through the entire absorber layer was successfully obtained. Additionally, it is observed that the accompanied by excellent crystallinity improved significantly due to the pronouncedly reduced carrier recombination loss at grain boundaries. As a consequence, the power conversion efficiency (PCE) of the CAZTSSe photovoltaic device is successfully increased from 10.35% (oxide route) to 11.32% (acetate route). Importantly, our work attests to the feasibility of tuning the crystallization of the CZTSSe film by simple chemistry.
材料结晶度是决定吸收体材料光电性能和光伏器件整体性能的首要因素。然而，在铜锌锡硫硒（CZTSSe）光伏器件中，广泛观察到吸收体的双层或三层结构，这通常对电池性能有害，因为晶界处光生载流子复合的概率显著增加。在此，我们的实验表明，在新型（铜，银）锌锡硫硒（CAZTSSe）材料中引入阴离子会导致晶粒尺寸和结晶度增加。令人鼓舞的是，在前驱体溶液中使用醋酸盐原料，获得了均匀、致密且无针孔的CAZTS前驱体薄膜，并且这些薄膜的光滑度超过了通过氧化物路线制备的薄膜。更重要的是，硒化后CAZTSSe薄膜的结晶得到了显著增强，成功获得了贯穿整个吸收体层的大晶粒。此外，观察到由于晶界处载流子复合损失显著降低，伴随着优异的结晶度也有显著提高。因此，CAZTSSe光伏器件的功率转换效率（PCE）成功地从10.35%（氧化物路线）提高到了11.32%（醋酸盐路线）。重要的是，我们的工作证明了通过简单的化学方法调节CZTSSe薄膜结晶的可行性。
