Study of ALD-grown Tin Oxide as an Electron Selective Layer for NIP Perovskite-Based Solar Cells

This work presents a comparative study between tin(IV) oxide
$(\mathbf{SnO_{2}})$
thin films deposited either by solution process or by Atomic Layer Deposition (ALD) for an application as an electron selective layer in perovskite/silicon tandem solar cells. This study is motivated by the usually lower performances of solar cells using electron selective layer (ESL) made of ALD-grown
$\mathbf{SnO_{2}}$
compared to ones using a solution-processed ESL. Chemical, electrical, optical and topographical properties of each type of film were investigated. In an attempt to link thin film properties to device characteristics single-junction perovskite solar cells and perovskite/silicon tandem solar cells were fabricated. Despite the high-quality conductivity and optical properties of ALD-grown
$\mathbf{SnO_{2}}$
, perovskite-based solar cells employing such film showed limited performances. Characterization of perovskite films properties grown on both type of
$\mathbf{SnO_{2}}$
did not rise significant differences and tend to indicate some hindering factors at the ALD-grown
$\mathbf{SnO_{2}}$
interface with perovskite. Specifically, a larger workfunction for ALD-grown
$\mathbf{SnO_{2}}$
may create a potential barrier for electron extraction at perovskite interface