Improvement on the performance and stability of carbon-based perovskite solar cells by using APH additives

After over a decade of development, the photoelectric conversion efficiency (PCE) of perovskite solar cell has exceeded 26.7 %. However, long-term stability remains a critical challenge for commercialization. During the annealing process of perovskite films prepared by the solution method, defect states will be generated on the surface and bulk phases. These defects induce ion migration and degradation, primarily due to the erosion by the moisture and oxygen, which seriously affects the efficiency and stability. Therefore, we introduced 4-sulfonamidophenylhydrazine hydrochloride (APH) as an additive molecule into the ternary cation Cs 0.05 (FA 0.83 MA 0.17 ) 0.95 Pb(I 0.83 Br 0.17 ) 3 precursor solution. The results indicate that the O S=O, NH 2 and NH groups in APH can effectively passivate the charged defects by Lewis acid-base coordination with the uncoordinated Pb 2 + in the perovskite film. The crystallization process of perovskite was modulated, and thin films with increased grain size were obtained. The non-radiative recombination center inside the device is reduced. Additionally, the interfacial energy levels of the APH-modified perovskite films are better matched, which increases the separation driving force of photogenerated carriers. The introduction of APH not only passivates the defects in perovskite films but also effectively separates and transports carriers, which significantly enhances the device's open-circuit voltage (V oc ) and short-circuit current density (J sc ). Ultimately, the 0.2 mol% APH-modified device achieved the highest PCE of 14.15 %, showing 8.7 % increase in efficiency. The optimized device retains 87 % of the initial efficiency after 1200 h of storage, which is 36 % higher than that of the original device. The O S=O, NH 2 and NH groups in APH can effectively passivate the charged defects by Lewis acid-base coordination with the uncoordinated Pb 2+ in the perovskite film. The non-radiative recombination center inside the device is reduced. Moreover, the energy level structure of the modified perovskite film is positively shifted, which increases the carrier separation driving force and makes the carrier separation and transport more efficient. Ultimately, the maximum efficiency of the device based on the optimized perovskite film was 14.15 %. • The crystalline quality of perovskite was improved by introducing APH. • The APH passivates the defects by Lewis acid-base coordination with the uncoordinated Pb 2+ . • Modification of the device with APH achieved an optimized efficiency of 14.15 %. • After 1200 h storage, the optimized device maintains 87 % initial efficiency.