Performance Improvement of All-Inorganic, Hole-Transport-Layer-Free Perovskite Solar Cells Through Dipoles-Adjustion by Polyethyleneimine Incorporating

Abstract

In the increasingly rapid development of perovskite solar cells (PSCs), all-inorganic PSCs, especially Br-rich all-inorganic PSCs, not only inherit the advantages of an adjustable bandgap, and excellent light absorption, but also has superior stability. To find a simple-process and low-cost way to increase perovskite performance, we try to adjust the conduction band of CsPbIBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> with the help of dipoles induced by PEI incorporating. Furthermore, we use carbon as the negative electrode to abandon the noble metal and hole transport layer (HTL). Finally, the solar cells with the structure of fluorine-doped tin oxide (FTO)/TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /CsPbIBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /Carbon are prepared. The V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>oc</i></sub> and FF of the carbon-based, HTL-free and all-inorganic PSCs with polyethyleneimine (PEI) incorporating have an obvious improvement, and the champion device can get an efficiency of 7.5% with peak V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>oc</i></sub> of 1.2 V and maximum FF of 65%, which is far beyond the one without PEI incorporating. Our work hopes to give an effective method to produce a simple, cost-effective design for PSCs.