Stable tin perovskite solar cells developed via additive engineering

Abstract

Tin perovskite solar cells (TPSCs) are promising for lead-free perovskite solar cells (PSCs) and have led to extensive research; however, the poor crystallinity and chemical stability of tin perovskites are two issues that prevent stable TPSCs. In this study, we outline a new process that addresses these issues by using tin(II) acetate (Sn(Ac) 2 ) in place of the conventional SnF 2 precursor additive. Compared with SnF 2 , Sn(Ac) 2 improves the crystallinity and stability of tin perovskite with fewer defects and better charge extraction. Using this process, we developed a device that has a higher external quantum efficiency for charge extraction compared with the control devices and a power conversion efficiency of 9.93%, which maintained more than 90% of its initial efficiency after 1000 h operation at the maximum power point under standard AM 1.5G solar illumination.

Additive Engineering with Triple Cations and Bifunctional Sulfamic Acid for Tin Perovskite Solar Cells Attaining a PCE Value of 12.5% without Hysteresis

“…Tin perovskite solar cells (TPSCs) have become some of the most promising candidates for lead-free perovskite solar cells as a next-generation photovoltaic technology. − However, the intrinsic problems of TPSCs, such as Sn 2+ /Sn 4+ oxidation, rapid crystallization, poor stability, and so on, need to be solved to promote the device performance for TPSCs. − Many approached have been reported to tackle these problems; − among them, additive engineering is a promising approach to passivate the surface defects, reduce Sn 4+ back to Sn 2+ , modulate crystallization, form a surface-protected low-dimensional perovskite, and so forth. − Tin fluoride (SnF 2 ) and ethylene diammonium diiodide (EDAI 2 ) are two of the most common additives to prevent Sn 2+ /Sn 4+ oxidation as well as to regulate the crystallization for TPSC. , In addition to these two additives, others such as cationic, anionic, and multifunctional additives have been widely considered for TPSCs. ,,− We have previously reported organic cations such as guanidinium (GA), 2-hydroxyethylammonium (HEA), and aziridinium (AZ) as A-site cations to cocrystallize with formamidinium (FA) to form cocationic tin perovskites for enhanced performance and stability for TPSCs. In the present study, a new organic cation, imidazolium (IM), was implemented to mix with FA to form a cocationic tin perovskite.…”

Challenges and strategies toward long-term stability of lead-free tin-based perovskite solar cells

“…This same behaviour may be shared by other SnX 2 additives also successfully implemented to enhance the stability of Sn-HPs. These include SnAc 2 (Ac = acetate), SnAcac 2 (Acac = Acetylacetonate) and Sn(SCN) 2 [87][88][89] . In fact, other non-Sn-based additives bearing these same counter-anions have also shown benefits on device performance, highlighting the potential of bifunctional additives for versatile applications in precursor solutions 10,90 .…”

Sn‐Based Perovskite Halides for Electronic Devices

“…Sn(CH 3 COO) 2 has the same effect as SnF 2 and can prevent Sn 2+ oxidation and yield even higher photovoltaic response in TPSCs. [ 130 ] Nevertheless, note that excess SnF 2 , SnCl 2 , or Sn(CH 3 COO) 2 might induce phase segregation in THP films. Hence, an optimal amount of such additives for the fabrication of high‐quality THP films is much necessary.…”