Low-temperature preparation of HTM-free SnO2-based planar heterojunction perovskite solar cells with commercial carbon as counter electrode

In order to meet the demand for fabricating flexible and wearable solar cell products, low-temperature preparation technology of perovskite solar cells (PSCs) has become critical. As a highly promising electron transport layer (ETL) material, SnO 2 has many advantages, such as high charge mobility, wide band gap, and could be prepared at relatively low temperatures. However, the application of SnO 2 -based PSCs is limited by the expensive hole transport material (HTM) and electrode material (e.g. spiro-OMeTAD and gold) in the common device structure. In this paper, with SnO 2 as the ETL, cheap carbon as the counter electrode, HTM–free PSCs structured as FTO/SnO 2 /CH 3 NH 3 PbI 3 /Carbon was fabricated by the full low-temperature technology. The thickness of the SnO 2 ETL was optimized by adjusting the concentration of the SnO 2 precursor. The highest PCE of 8.32% was obtained and after 32 days in an air environment without packaging, the PCE still remained approximately 92% of its original performance. The factors affecting the stability of the cell were analyzed according to the structure of the PSCs.