Graphdiyne oxide doped SnO₂electron transport layer for high performance perovskite solar cells

High-performance planar perovskite solar cells (PSCs) are dependent on the properties of electron transport layers (ETLs). Here, we report an effective interface engineering strategy by incorporating an oxidized form of graphdiyne into a SnO2 ETL. In addition to the unique structural properties of graphdiyne, graphdiyne oxide (GDYO) is characteristic of additional hydrophilic carboxy and hydroxy functional groups that may form chemical bonds with uncoordinated Sn. The interaction thereof is able to reduce the oxygen vacancy within SnO2, thereby passivating the surface defects of SnO2; this promotes electron transport while also suppressing non-radiative recombination. Notably, the work function of the GDYO-doped SnO2 film matches well with the perovskite conduction band, resulting in a high open circuit voltage. As a consequence, the GDYO-containing device demonstrated a high PCE of 21.23% with a VOC of 1.13 V, a JSC of 24.49 mA cm-2 and an FF of 76.85%, superior to those of the control device without GDYO. Furthermore, the unencapsulated device maintained 84% of the initial efficiency after 80 °C for 24 days and 71% after continuous illumination for 160 h. This work provides guidance for developing efficient and stable perovskite devices from the perspective of optimizing interface properties, presenting great potential of functionalized graphdiyne for practical applications.