Multifunctional tyrosine modified SnO2 to improve the performance of perovskite solar cells

Recently, it has been demonstrated that the use of SnO2 as the electron transport layer (ETL) of perovskite (PSK) solar cells (PSCs) yields high efficiency, which is comparable to that of the TiO2 layer with the same structure. At the same time, the SnO2-based PSCs show improved stability. Herein, the defects at the device interface are reduced and the efficiency of the planar PSCs is enhanced by improving the interface contact between the ETL and the perovskite (PSK) layer. As an essential amino acid, tyrosine (Tyr) is introduced into SnO2 to fill the oxygen vacancies in SnO2 films and improve the nucleation of PSK. From our analysis, it was found that the interface contact between the SnO2 ETL and the PSK layer was increased and the defects at the interface were reduced. In addition, it was demonstrated that the introduction of Tyr could effectively suppress the charge recombination and improve the electron extraction efficiency. As a result, a champion power conversion efficiency (PCE) of 22.17% was obtained from Tyr modified PSCs, owing to the enhanced PSK film quality and carrier extraction efficiency. On top of that, the Tyr-modified device still maintained 87% of the initial recorded PCE, which was stored in the ambient air (25 °C, 25% ± 5% RH) for 864 h without encapsulation.