Enhancing the efficiency and stability of p-i-n triple cation perovskite solar cells using benzyl cyanoacetate passivation agent

It is extremely difficult to realize high-performance perovskite solar cells (PeSCs) due to a large number of defects of perovskite. Thus, perovskite defects should be passivated as much as possible. In this study, effective cyano ([sbnd]CN), benzene ring, and carbonyl (C[dbnd]O) functional groups were newly introduced to benzyl cyanoacetate (BCA) to prepare a multifunctional BCA passivation agent. The influence of functional group of BCA passivation molecule on perovskite and PeSCs was systemically studied using cyanoethyl acrylate (CA) with [sbnd]CN without benzene ring and benzyl acrylate (BA) with benzene ring without [sbnd]CN as reference molecules. Through various analyses, we found that the novel BCA passivation agent with both [sbnd]CN and benzene ring passivated perovskite defects the most efficiently. Thus, the combination of each effective functional group can synergistically passivate more perovskite defects. As a result, PeSCs created using BCA showed improved power conversion efficiency (PCE) from 18.38 % to 20.23 %. Additionally, PeSC with BCA retained 70 % of the initial PCE after ∼2034 h of air exposure test, 80 % of the initial PCE after ∼193 h of heat aging test, and 60 % of the initial PCE after ∼72 h of light-soaking test, demonstrating better stability than PeSC without BCA in air/heat/light-soaking stability.