Tin dioxide (SnO2), with its high electrical conductivity and low photocatalytic activity, has been reported as one of the best candidate materials for efficient electron transport layers (ETLs) in perovskite solar cells (PSCs). While state-of-the-art SnO2 layers are achieved by chemical bath deposition with tunable properties, commercially available SnO2 nanocrystals (NCs) with low tunability still face the need for further improvement.

Zhao Yixin and colleagues at Shanghai Jiao Tong University have reported highly crystallized Cl-doped SnO2 NCs that can form very stable aqueous dispersions with shelf life up to one year without any stabilizers, facilitating the fabrication of efficient PSCs. Compared to commercial SnO2 NCs, intrinsic Cl-doped SnO2 NCs effectively suppressed the barrier at the buried interface between the perovskite and ETL and reduced trap state density, regardless of the extrinsic Cl doping conditions.

As a result, stable PSCs based on these Cl-doped SnO2 NCs achieved champion efficiencies up to ca. 25% for small cells (0.085 cm2) and ca. 20% for mini modules (12.125 cm2), demonstrating their promising potential as ETL candidates for high-performance perovskite photovoltaics.