Study Of Narrow Bandgap Perovskite Solar Cells Based On Inorganic Charge Transport Layer

In the past decade,the photoelectric conversion efficiency of perovskite solar cells has increased rapidly from 3.8%to 25.5%.With the development of research on perovskite solar cells,perovskite solar cells can be divided into wide bandgap,conventional bandgap and narrow bandgap.As an important sub-cell in the perovskite/perovskite tandem solar cells,Pb-Sn mixed narrow band gap perovskite solar cells have received extensive attention.However,the stability of Pb-Sn mixed narrow band gap perovskite solar cells is poor.One of the reasons is that most of the Pb-Sn mixed narrow bandgap perovskite solar cells adopt organic charge transport layers with poor stability,such as PEDOT-PSS.The other reason is that Sn²⁺can be oxidized to Sn⁴⁺,which leads to the degradation of devices performance.Therefore,the development of an inorganic charge transfer layer with low cost and stable performance is an effective method to improve the stability of Pb-Sn mixed narrow bandgap perovskite solar cells.In addition,the device structure design to prevent Sn²⁺oxidation is also very important for improving the stability of Pb-Sn mixed narrow band gap perovskite solar cells.To solve the above problems,the inorganic hole transport layer was used to replace the traditional organic hole transport layer to improve the stability of Pb-Sn mixed narrow bandgap perovskite solar cells.In addition,the dense inorganic electron transport layer Sn O₂ prepared by ALD technology was used to improve the antioxidant capacity of Pb-Sn mixed narrow bandgap perovskite solar cells.The main research contents and results are as follows:1.Nickel oxide nanocrystals with excellent photoelectric properties were synthesized by co-precipitation method,and for the first time,the nickel oxide nanocrystals prepared by low-temperature solution method were applied as the hole transport layer in Pb-Sn mixed narrow bandgap perovskite solar cells.Using nickel oxide as hole transport layer not only achieves high performance devices with an efficiency of 17.4%,but also improves the thermal stability and long-term stability of the devices,which shows almost negligible degradation after 102 days of storage in nitrogen glove box.Under the condition of 85℃for 200 min,the efficiency of the detection device only attenuates slightly.2.The inorganic electron transport layer Sn O₂ with high thermal stability and high compactness was prepared by ALD technology.The thermal stability and oxidation resistance of the single-junction Pb-Sn mixed narrow bandgap perovskite cells prepared based on ALD-Sn O₂ are significantly improved.After 160 h of oxidation in dry air,the single-junction Pb-Sn mixed narrow bandgap perovskite cells can still maintain the initial efficiency of 85%.In addition,under 85℃,the encapsulated perovskite/perovskite tandem solar cells prepared based on ALD-Sn O₂ maintain 80%of their initial efficiency.