Park Jeong Eun, Park So Mang, Bae Eun Ji, Lim Donggun
Department of Electronic Engineering, Korea National University of Transportation, 50 Daehak-ro, Chungju-si, Chungbuk, 27469, Korea.
Department of IT Convergence, Korea National University of Transportation, 50 Daehak-ro, Chungju-si, Chungbuk, 27469, Korea.
J Nanosci Nanotechnol. 2020 Nov 1;20(11):6659-6664. doi: 10.1166/jnn.2020.18764.
Zinc Sulfide (ZnS) is an environmentally friendly material with a wide bandgap ( = 3.7 eV) comparable to that of cadmium sulfide (CdS) (2.4 eV), which is conventionally used as buffer layer in Cu(In,Ga)Se2 (CIGS) thin film solar cells. Conventional ZnS buffer layers are manufactured using thiourea, and, these layers possess a disadvantage in that their deposition rate is lower than that of CdS buffer layers. In this paper, thioacetamide (TAA) was used as a sulfur precursor instead of thiourea to increase the deposition rate. However, the ZnS thin films deposited with TAA exhibited a higher roughness than the ZnS thin films deposited with thiourea. Sodium citrate was therefore added to increase the uniformity and decrease the roughness of the former ZnS thin films. When sodium citrate was used, the thin films demonstrated a high transmittance via the controlled generation of particles. In the case of TAA-ZnS thin films doped with a sodium citrate concentration of 0.04 M, the granules on the surface disappeared and these thin films were denser than the TAA-ZnS thin films deposited with a lower sodium citrate concentration. It is considered that the rate of the ion-by-ion reaction increased due to the addition of sodium citrate, thereby resulting in a uniform thin film. Consequently, TAA-ZnS thin films with thicknesses of approximately 40 nm and high transmittances of 83% were obtained when a sodium citrate concentration of 0.04 M was used.
硫化锌（ZnS）是一种环境友好型材料，其宽带隙（3.7电子伏特）与硫化镉（CdS）（2.4电子伏特）相当，硫化镉传统上用作铜铟镓硒（CIGS）薄膜太阳能电池的缓冲层。传统的ZnS缓冲层是使用硫脲制造的，并且这些层存在沉积速率低于CdS缓冲层的缺点。在本文中，使用硫代乙酰胺（TAA）作为硫前驱体代替硫脲以提高沉积速率。然而，用TAA沉积的ZnS薄膜比用硫脲沉积的ZnS薄膜具有更高的粗糙度。因此添加柠檬酸钠以提高前者ZnS薄膜的均匀性并降低粗糙度。当使用柠檬酸钠时，薄膜通过控制颗粒的生成表现出高透射率。在掺杂浓度为0.04 M柠檬酸钠的TAA-ZnS薄膜的情况下，表面上的颗粒消失，并且这些薄膜比用较低柠檬酸钠浓度沉积的TAA-ZnS薄膜更致密。据认为，由于添加柠檬酸钠，逐离子反应的速率增加，从而产生均匀的薄膜。因此，当使用0.04 M的柠檬酸钠浓度时，获得了厚度约为40 nm且高透射率为83％的TAA-ZnS薄膜。
