Surface passivation for carbon-based perovskite solar cells by using propylamine hydroiodide: Improved performance and stability

Perovskite films fabricated by the solution-based approach usually contain a high density of defects, and as the top surface is exposed to the external environment, this region is where major defects are most easily formed. Organic ammonium salts can be used as materials for interfacial defect passivation. This study employed propylamine hydroiodide (PAI) to passivate the ternary perovskite's surface. PAI's interfacial passivation can effectively improve the interface defect and obtain the better film quality. Meanwhile, the incorporation of PAI can efficiently diminish the film's surface roughness, which is beneficial for the excellent contact at the interface. Post-PAI treatment effectively reduces the non-radiative recombination, markedly improving device stability and PCE. The final results show that the highest efficiency (PCE) after PAI passivation is 15.72 %, the open circuit voltage (V OC ) is 0.98 V, the short circuit current (J SC ) is 20.96 mA/cm 2 , and the filling factor FF is 76.51 %, which is 16.1 % higher than that of un-passivated devices. And in the case of light storage for more than 2000 h without packaging, PCE loss is only 14.5 %, showing significant long-term stability.