Ming Li,Qingyan Zhang,Haoran Ruan,Xiandong Wang,Yongping Liu,Zhenhuan Lu,Jiefeng Hai
The advantage of 2D-2D heterojunction over 2D-0D and 2D-1D heterojunction is that it has larger interface area, which results in the shorter migration distance of photo-induced charge carriers, and can therefore separate the electron-hole pairs more effectively. In this work, to form 2D-2D heterojunction , PbS nanosheets were grown in situ on 2D MoS 2 layers via. solvothermal process. The formation of 2D MoS 2 -2D PbS composites has been confirmed by XRD , Raman, TEM , and EDS analysis . The area of PbS nanosheets attached on MoS 2 can be controlled by changing the concentration of PbS precursor in reaction solution. Compared with pristine MoS 2 , MoS 2 -PbS composites showed improved light absorption property and enhanced photocatalytic ability using methylene blue as the target of degradation. The optimized composite displayed a photocurrent 5 times higher than that of pristine MoS 2 .
Xuanling Liu,Ziyi Wu,Han Zhong,Xuanyu Wang,Jianfei Yang,Ziling Zhang,Jianhua Han,Dan Oron,Hong Lin
Nanomaterials such as quantum dots and 2D materials have been widely used to improve the performance of perovskite solar cells due to their favorable optical properties, conductivity, and stability. Nevertheless, the interfacial crystal structures between perovskites and nanomaterials have always been ignored while large mismatches can result in a significant number of defects within solar cells. In this work, cubic PbS nanosheets with (200) preferred crystal planes are synthesized through anisotropy growth. Based on the similar crystal structure between cubic PbS (200) and cubic-phase formamidinium lead triiodide ( α -FAPbI 3 ) (200), a nanoepitaxial PbS nanosheets-FAPbI 3 heterostructure with low defect density is observed. Attribute to the epitaxial growth, PbS nanosheets-FAPbI 3 hybrid polycrystalline films show decreased defects and better crystallization. Optimized perovskite solar cells perform both improved efficiency and stability, retaining 90% of initial photovoltaic conversion efficiency after being stored at 20 °C and 20% RH for 2500 h. Notably, the significantly improved stability is ascribed to the interfacial compression strain and chemical bonding between (200) planes of PbS nanosheets and α -FAPbI 3 (200). This study provides insight into high-performance perovskite solar cells achieved by manipulating nanomaterial surfaces.
Xuanling Liu,Han Zhong,Xuanyu Wang,Jianfei Yang,Ziling Zhang,Jianhua Han,Dan Oron,Hong Lin
Regulating strain in perovskite films via utilizing the crystal structure relationship between solid-phase materials (SPMs) and perovskite is an effective method to achieve high-performance perovskite solar cells. It is crucial to investigate and manipulate the heterointerfaces between perovskites and SPMs since the mismatched crystal structure and energy band structure of SPMs will bring recombination sites to the heterointerfaces. In this work, CdS-modified PbS nanosheets (CPS) were prepared through cation exchange with (200)-preferred PbS nanosheets. The wide-band gap CdS charge-blocking layer of CPS nanosheets distributed at the grain boundaries effectively passivates the heterointerfaces in FAPbI3-CPS heterostructures (FAPI-CPS). Further, it potentially blocks carrier transportation and suppresses carrier recombination at grain boundaries and in FAPbI3-PbS nanosheet heterointerfaces. Attributed to the CdS layer, the FAPI-CPS devices achieve an enhanced power conversion efficiency. CPS nanosheets with an interplanar spacing slightly smaller than that of α-FAPbI3 could provide compressive strain to FAPbI3 at the FAPI-CPS heterointerfaces, leading to significantly improved device stability. The unencapsulated FAPI-CPS solar cells maintained 92% of their initial PCE after being stored at 20 ± 5 °C, 20 ± 5% RH for 2500 h.
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