Interfacing green synthesized flake like-ZnO with TiO2 for bilayer electron extraction in perovskite solar cells

Artikel i vetenskaplig tidskrift, 2020

To improve the performance of PSCs, it is essential to prevent the carrier recombination losses at the interfaces of the transparent metal oxide electrode/electron transport layer (ETL)/active absorber perovskite layer. This present work reports on the green synthesis approach used for the preparation of flake like-ZnO nanostructure (GF-ZnO NS), naturally extracted from the leaf of Albizia Amara, used as a reducing cum capping agent. Herein, we have introduced an n-type GF-ZnO NS material as an efficient electron transport interfacial layer (bi-ETL) at the ETL/perovskite junction in the fabricated perovskite solar cells (PSCs). The structure of the fabricated PSC device is as follows: glass/ITO/bi-ETL (c-TiO2/GF-ZnO NSs)/CH3NH3PbI3-xClx/spiro-MeOTAD/Au. A comparative study has also been carried out by deploying electron transport materials such as c-TiO2 and GF-ZnO NSs separately. From this, it has been found that the bi-ETL perovskite solar cell devices achieved a maximum power conversion efficiency (PCE) of 7.83% with an open-circuit voltage (VOC) of 0.728 V, a short circuit current density (JSC) of 20.46 mA cm-2 and a fill factor (FF) of 52.61% whereas, the c-TiO2, GF-ZnO NSs and the chemically reduced CR-ZnO ETL based devices achieved a PCE of 4.84%, 5.82% and 6.81%, respectively. The better performance obtained for the bi-ETL based devices is ascribed to the enhanced carrier extraction and the reduced recombination losses at the interface between the ETL and the active perovskite layer.