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, SnO2 has many advantages, such as high charge mobility, wide band gap, and could be prepared at relatively low temperatures. However, the application of SnO2-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 SnO2 as the ETL, cheap carbon as the counter electrode, HTM-free PSCs structured as FTO/SnO2/CH3NH3PbI3/Carbon was fabricated by the full low-temperature technology. The thickness of the SnO2 ETL was optimized by adjusting the concentration of the SnO2 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. (C) 2019 Elsevier B.V. All rights reserved.