| Organic-inorganic lead halide perovskites have been widely investigated in optoelectronics due to its advantages of high absorption coefficient,adjustable band gap and so on.At present,the certificated perovskite solar cells efficiency has reached 24.2%.In this thesis,new interface transport layers are mainly studied through interface engineering and energy level engineering.Novel electron transport layers?ETLs?are developed to solve charge transport mismatch problem in order to enhance the photoelectric conversion efficiency of the device.Further,the hydrophobic hole transport layers?HTLs?are developed to improve the long-term stability of perovskite devices.Electron mobility in organic-inorganic mixed-cation perovskite devices is lower than hole mobility,which results in charge transport mismatch and restricts the development of perovskite device efficiency.Aiming at this problem,we mainly develop novel ETLs to improve the transmission ability of electrons in device,and then enhance the device efficiency.Firstly,naphthalimide chemical dispersed graphene was used to modify SnO2 to obtain the conductive water-soluble SnO2-graphene ETL with a high electron mobility of4.67×10-4 cm2·V-1·s-1,which was used in n-i-p planar devices.The van der Waals interaction was formed at perovskite/ETL interface,fixing the inorganic framework[PbI6]4-at the perovskite/ETL interface,which would exhibit a retarded interfacial charge recombination and eliminate volage drop loss.As a result,the fill factor of perovskite single junction device was up to 82.1%,and the photovoltaic conversion efficiency reached 20.16%.Secondly,we utilized self-assembly stacking deposition method to prepare SnS2 two-dimentional ETL material(electron mobility up to 7.85×10-4 cm2·V-1·s-1),which was used in n-i-p planar devices.The micro-mosaic structure was formed at the interface between perovskite crystal and SnS2 due to the special Pb-S interaction,which contributed to the uniform perovskite crystal growth,an efficient electron extraction and suppress the voltage drop loss.More balanced charge transport has been found in SnS2-based devices.The perovskite solar cells achieved a 20.12%power conversion efficiency,along with an open-circuit voltage of 1.161V.This part of work provides important guidance for further research on ETL used in solving the problem of device carrier mismatch and improving the performance of perovskite solar cell devices.The development of perovskite devices is seriously hindered by its poor long-term stability.For n-i-p planer devices,researching on the novel HTLs is an important method to reduce the influence of external environment on perovskite absorbing layer and improve devices'long-term stability.In this regard,we carried out the following work:HTLs were constructed by using pyrrolepyrrolidone with different donor units and?bridges,D-A-D HTL were developed by using phenothiazine or triphenylamine as donor and dithienopyrrolobenzothiadiazole?DTPBT?as receptor,and D-A-D HTL was combined by using triphenylamine as donor and benzotriazole or its derivtives as receptor.These HTLs were used in ITO/ETL/MAPbI3-xClx/HTL/Au perovskite devices respectively,and the corresponding devices showed good long-term stability.Among these HTLs,HTL based on phenothiazine and DTPBT possessed the strong push/pull electron capability,which facilitated efficient hole extraction ability of its devices.The devices achieved an efficiency of 14.2%and exhibited a long-term stability without encapsulation?80%initial efficiency after 280 hours?.HTL based on triphenylamine and dithienopyrrolobenzotriazole achieved an undoped cell efficiency 13.22%and its excellent hydrophobicity?contact angle with water is up to 105°?improves the stability of the unencapsulate device.This part of work provides important theoretical guidance for improving the long-term stability of perovskite devices by developing novel hydrophobic HTLs. |
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