Improved Efficiency and Stability of Perovskite Solar Cells Induced by CO Functionalized Hydrophobic Ammonium‐Based Additives

Abstract

Because of the rapid rise of the efficiency, perovskite solar cells are currently considered as the most promising next-generation photovoltaic technology. Much effort has been made to improve the efficiency and stability of perovskite solar cells. Here, it is demonstrated that the addition of a novel organic cation of 2-(6-bromo-1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)ethan-1-ammonium iodide (2-NAM), which has strong Lewis acid and base interaction (between CO and Pb) with perovskite, can effectively increase crystalline grain size and reduce charge carrier recombination of the double cation FA MA PbI Br perovskite film, thus boosting the efficiency from 17.1 ± 0.8% to 18.6 ± 0.9% for the 0.1 cm cell and from 15.5 ± 0.5% to 16.5 ± 0.6% for the 1.0 cm cell. The champion cell shows efficiencies of 20.0% and 17.6% with active areas of 0.1 and 1.0 cm , respectively. Moreover, the hysteresis behavior is suppressed and the stability is improved. The result provides a promising route to further elevate efficiency and stability of perovskite solar cells by the fine tuning of triple organic cations.

Formamidinium‐Based Lead Halide Perovskites: Structure, Properties, and Fabrication Methodologies

“…Similarly, hydrophobic additives that provide a protective coating for perovskite grains, such as 1‐methyl‐3‐(1H,1H,2H,2H‐nonafluorohexyl)imidazolium iodide, can be used to enhance the stability of the mixed‐perovskite solar cells . Other additives include TFEA cations, which result in the formation of a quasi‐layered perovskite with enhanced moisture resistance, N ‐methylimidazole, which slows down the crystallization and facilitates the growth of larger perovskite grains, and a novel organic cation, which also facilitates the growth of large grain sizes …”

Reducing Detrimental Defects for High‐Performance Metal Halide Perovskite Solar Cells

“…The surface under‐coordinated Pb 2+ (Figure b and Figure a–c) is the main source of trap states and several chemicals have been proposed to heal this particular type of defect. A selection of organic molecules containing Lewis base functional groups, such as pyridine, thiophene, thiourea, 6,6,12,12‐tetrakis(4‐hex‐ylphenyl)‐indacenobis(dithieno[3,2‐b;2,3‐d]thiophene) end‐capped with 1,1‐dicyanomethylene‐3‐indanone units with 0 to 2 fluorine substituents (INIC), perylene diimide and dithienothiophene (PPDIDTT), benzodithiophene and diketopyrrolopyrrole with linear alkylthio substituents (BDTS‐2DPP), 1,3,4‐thiadiazolidine‐2,5‐dithione (TDZDT), organic semiconducting non‐fullerene acceptor molecule named IT‐M, 3,9‐bis(2‐meth‐ ylene‐(3‐(1,1‐dicyanomethylene)‐indanone))‐5,5,11,11‐tetrakis(5‐hexylthienyl)‐dithieno[2,3‐d:2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′] dithiophene (ITIC‐Th), 2‐(6‐bromo‐1,3‐dioxo‐1H‐benzo[de]isoquinolin‐2(3H)‐yl)ethan‐1‐ammonium iodide (2‐NAM), and others were employed. Lewis base can coordinate with Pb 2+ through lone pair electrons neutralizing its positive charge leading to subsequent annihilation of electronic trap states.…”

Highly Efficient and Stable Solar Cells Based on Crystalline Oriented 2D/3D Hybrid Perovskite

“…Consequently, it may be a promising strategy to develop 2D/3D hybrid perovskite materials by combining the advantage of high efficiency of 3D perovskite and high stability of 2D perovskite. However, a search of alternative yet effective organic spacer cations as well as device engineering to fabricate high performance 2D/3D hybrid perovskite solar cells have been experimentally challenging …”