All-Perovskite Tandems Enabled by Surface Anchoring of Long-Chain Amphiphilic Ligands

Abstract

: Perovskite solar cells (PSCs) in the pin structure are limited by nonradiative recombination at the electron transport layer (ETL) interface, which is exacerbated in narrow-bandgap ( ∼ 1.2 eV) Pb − Sn PSCs due to surface Sn oxidation and detrimental p-doping. Photoluminescence quantum yield studies herein indicated that ethane-1,2-diammonium (EDA) passivation only partially alleviates perovskite/ETL energetic losses. We pursued passivation of the defect-rich perovskite:ETL interface to reduce nonradiative losses; our target was to combine chemical coordination of Sn sites with the introduction of an interlayer, which we implemented by introducing long-chain carboxylic acid ligands at the perovskite surface. Treatment with oleic acid (OA) led to reduced recombination at the perovskite/ETL interface and evidence of Sn 2+ coordination. This reduced the V OC deficit of Pb − Sn PSCs to 0.34 V, resulting in a 0.89 V V OC and PCE of 23.0% (22.4% stabilized). Incorporating the OA-treated Pb − Sn layer into a monolithic all-perovskite tandem, we report a 27.3% PCE (26.4% certified) and a V OC of 2.21 V. B andgap tuning in metal-halide perovskites ( ∼ 1.2 − 3.0 eV) has resulted in

Junke Wang

Principal Investigator

Junke Wang leads the LENS Lab at SCUT, working on optoelectronic devices for energy and light technologies.