异质结性能调控诱导开路电压提升的高效Sb2Se3薄膜太阳电池研究

硒化锑（Sb2Se3）具有低毒、原材料丰富和光电性能优异等优点，被广泛认为是最具有发展潜力的薄膜太阳电池吸收层材料之一。尽管目前Sb2Se3薄膜太阳电池的光电转换效率已达到9.2%，但与碲化镉、铜铟镓硒和钙钛矿等太阳电池相比仍有较大差距。较低的开路电压是限制Sb2Se3电池器件效率进一步突破的核心瓶颈，而造成器件开路电压损耗严重的主要原因之一是光生载流子在异质结界面处的高复合率。本项目提出采用磁控溅射后硒化法制备具有硒梯度的Sb2Se3光吸收层，钝化薄膜表面深能级缺陷，提高异质结成结质量，抑制光生载流子在异质结界面处的复合；此外，采用共溅射法沉积制备Zn1−xSnxOy薄膜代替传统CdS缓冲层，力图构造spike型能带排布从而有效减少光生载流子在异质结界面的复合，全面提升器件开路电压和整体性能，为发展环境友好、稳定高效的Sb2Se3薄膜太阳电池提供理论依据和实验基础。

Antimony selenide (Sb2Se3) is regarded as one of the key alternative absorber materials for thin film solar cells due to attractive features such as low-toxic, earth-abundant, excellent optical and electrical properties. However, the overall performance of Sb2Se3 devices is still far away from those of conventional efficient thin film solar cells e.g. CdTe, CIGS and perovskite despite the fact that the power conversion efficiency (PCE) of Sb2Se3 devices has reached to 9.2%. Unsatisfied open-circuit voltage is the key obstacle to hinder the device efficiency from further improving. High recombination rate of photogenerated carriers at heterojunction interface has been considered as one of the main reasons for severe open-circuit voltage deficit of Sb2Se3 devices. In this project, we aim to utilize magnetron sputtering followed by a post-selenization treatment to prepare high-quality Sb2Se3 absorber layer with a Se concentration gradient, which enable us to passivate deep defects on the film surface, improve the heterojunction quality and suppress photogenerated carrier recombination at the interface. Moreover, to further suppress carrier recombination at the heterojunction, Zn1−xSnxOy thin film will be deposited by co-sputtering a ZnO target and a SnO2 target to replace the conventional CdS buffer layer. By tuning the sputtering process carefully, a spike-like band structure and thus an improved open-circuit voltage as well as overall photovoltaic performance of the device will be achieved.