Improving the efficiency and stability of screen-printed carbon-based perovskite solar cells through passivation of electron transport compact-TiO2 layer with TiCl4

A homogenous and well-packed electron transport layer (ETL) is crucial in attaining high-performance perovskite solar cells (PSCs). Two vital tasks are carried out by ETL: excellent electron collection, and proficiently prevents the recombination of charge carriers. Hole transport layer (HTL) free screen-printed carbon-based perovskite solar cells (SP-C-PSCs) are particularly favored within the realm of PSCs due to their exceptional scalability, durability, and affordability. Titanium dioxide (TiO2) has been widely used as the ETL in these SP-C-PSCs due to its suitable band energy structure, ease of production, and low cost; nevertheless, it must be of high quality and uniformly deposited. Here experimental analytical study of PSCs was conducted, employed surface passivation to compact titania (c-TiO2) ETL using TiCl4 passivation agent through two different deposition techniques. This passivation is applied to lower its surface roughness, improve electron transport capability, increase crystallinity, reduce micro pores, exhibit better energy level alignment, and to reduce the recombination sites. Consequently, the device with surface passivation enhances the power conversion efficiency (PCE) and long-term ambient stability of PSCs by maximizing the c-TiO2 ETL electrical characteristics. It is also discovered that the passivated c-TiO2 layer has increased hydrophobicity and reduced the RMS surface roughness from 28.8 to 27.3 nm. The PCE of the fabricated SP-C-PSCs is improved by 32.34% through applying spin-coating TiCl4 passivation, and 21.74% enhancement is recorded by applying dip-coating TiCl4 passivation. Furthermore, after 1344 h of storage under ambient conditions without encapsulation, the device passivated with spin-coating retained 84.27%, the device passivated with dip-coating maintained 85.50%, while the reference device reserved just 75.84% PCE.