Effect of excessive Pb on the stability and performance of Pb-halide perovskite solar cells against photo-induced degrad
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Research Letter
Effect of excessive Pb on the stability and performance of Pb-halide perovskite solar cells against photo-induced degradation Aditya S. Yerramilli, School for Engineering of Matter, Transport and Energy, Arizona State University, AZ, USA Yuanqing Chen, School for Engineering of Matter, Transport and Energy, Arizona State University, AZ, USA; Department of Materials Physics & Chemistry, Xi’an University of Technology, Xi’an, China T. L. Alford , School for Engineering of Matter, Transport and Energy, Arizona State University, AZ, USA; Materials Science Graduate Program, African University of Science and Technology, Abuja, Nigeria Address all correspondence to T. L. Alford at [email protected] (Received 13 May 2018; accepted 7 December 2018)
Abstract Perovskite solar cells have evolved significantly since their inception. However, stability is still a major concern. We fabricated devices using a glass/ITO/PEDOT:PSS/MAPbI3/PCBM/Ag device configuration. Devices fabricated using the Pb-acetate precursors showed an efficiency of 13%. This work reports the effect of adding excess lead to the precursor and its impact on the light-induced degradation of efficiency. It is found that 5% excess lead is best for devices regarding the performance and stability and devices retained greater than 50% of the initial efficiency after 2 h of prolonged irradiation. We attribute this phenomenon to the formation of PbI2 which induces passivation in the grain-boundaries.
Introduction Perovskite solar cells (PVSCs) have turned to be highly promising solar advancements in recent years. This is owing to their highly economical manufacturing processes[1–3] while demonstrating excellent performance.[4–8] The challenge to advancement of PVSCs is that the devices are very unstable and efficiency goes down due to photo-degradation.[9–11] Several reports have emerged that confirm that a continuous exposure to sunlight leads to reduced performance.[12,13] Reasons for degradation can be due to numerous factors such as degradation of the PVSC itself according to Ito et al.,[14] which can be caused due to heat and light-induced factors.[15] Another reason that has been reported for poor performance is the degradation at the electrode and active region interface or charge transport layers (CTLs).[16] Additionally, other possible causes/mechanisms for degradation are ion migration and formation of trap states.[15,17–19] Lead iodide commonly forms as a product during the degradation process.[15,20] Several groups have shown means to improve performance and maintain it by employing compositional engineering and through addition of cross-linking additives and other precursor materials.[21–23] However, the aspects of photo-degradation need a more thorough investigation. As in real-world applications, high performance is expected under constant exposure and hence, degradation is a major reliability issue. In this work we used Pb-acetate as the main precursor and we have fabricated inverted architecture devices with indium-doped tin-oxide as the electrode
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