Greener, Nonhalogenated Solvent Systems for Highly Efficient Perovskite Solar Cells

Abstract

Apart from the high power conversion efficiencies (PCEs), [1][2][3] one of the most attractive features of ABX 3 (A = Cs, methylammonium (MA), and formamidinium (FA); B = Pb and Sn; and X = Cl, Br, and I) perovskites is the simplicity of fabrication. Perovskite thin films can be deposited through a variety of different techniques ranging from one-step [4][5][6][7][8] and two-step sequential methods, [9][10][11] vaporassisted solution processing, [12,13] and thermal gas-assisted evaporation. [9,[14][15][16][17][18] However, in a laboratory setting, one-step spin-coating remains the simplest and quickest route for high-quality perovskite layers. To improve film morphology, the spin-coating deposition has been optimized using solvent mixtures (e.g., dimethylformamide (DMF), dimethylsulfoxide (DMSO), γ-butyrolactone (GBL)), [19] and a variety of lead salt precursors. [20][21][22] Importantly, almost all currently reported All current highest efficiency perovskite solar cells (PSCs) use highly toxic, halogenated solvents, such as chlorobenzene (CB) or toluene (TLN), in an antisolvent step or as solvent for the hole transporter material (HTM). A more environmentally friendly antisolvent is highly desirable for decreasing chronic health risk. Here, the efficacy of anisole (ANS), as a greener antisolvent for highest efficiency PSCs, is investigated. The fabrication inside and outside of the glovebox showing high power conversion efficiencies of 19.9% and 15.5%, respectively. Importantly, a fully nonhalogenated solvent system is demonstrated where ANS is used as both the antisolvent and the solvent for the HTM. With this, state-of-the-art efficiencies close to 20.5%, the highest to date without using toxic CB or TLN, are reached. Through scanning electron microscopy, UV-vis, photoluminescence, and X-ray diffraction, it is shown that ANS results in similar mixed-ion perovskite films under glovebox atmosphere as CB and TLN. This underlines that ANS is indeed a viable green solvent system for PSCs and should urgently be adopted by labs and companies to avoid systematic health risks for researchers and employees.

Zinc Stannate Nanorod as an Electron Transporting Layer for Highly Efficient and Hysteresis-less Perovskite Solar Cells

“…[1][2][3][4][5] The steady improvement is mainly reached using interface engineering, compositional engineering, crystal engineering and the utilization of passivation agents. [6][7][8][9][10] This recently results in a PSC device with a certified PCE of 22.6%. 11 Among these techniques, the improvement of charge extraction properties in electron transporting layer (ETL) and light absorption in the device are the most effective approaches for boosting the photovoltaic parameters of PSCs.…”

Causes and Solutions of Recombination in Perovskite Solar Cells

“…Encouraged by the above purpose, a variety of methods were also developed to improve morphology and crystallization of perovskite films, such as deposition method (such as one‐step deposition, sequential deposition, vacuum deposition, vacuum‐flash solution processing, etc. ), optimization of precursor solvents and antisolvents, additive engineering, etc. In terms of optimization of precursor solvents and antisolvents, the formation of intermediate phase (CH 3 NH 3 I–PbI 2 –DMSO) was found to play an important role in achieving highly efficient PSCs .…”

“…In terms of optimization of precursor solvents and antisolvents, the formation of intermediate phase (CH 3 NH 3 I–PbI 2 –DMSO) was found to play an important role in achieving highly efficient PSCs . Subsequently, vast efforts were made to optimize the precursor solvents and antisolvents through investigating the intermediate phases . Except for device configuration, perovskite composition, fundamental procedure for preparing perovskite films and additive engineering, and interface engineering also play a crucial role in enhancing the PCE and stability of PSCs .…”

A prenucleation strategy for ambient fabrication of perovskite solar cells with high device performance uniformity

“…More significantly, this outstanding efficiency comes at an extremely low cost since the perovskite solar cells can be obtained by a solution-based fabrication process, triggering a global competition to translate the brilliant perovskite materials to innovative technologies [8][9][10][11] . However, researchers quickly found that the performance of PVSCs is quite sensitive to humidity, oxygen and solvent vapors, severely restricting the fabrication condition of such solar cells [12][13][14] . Normally, the oxygen and H 2 O should be below the ppm level to avoid their perceptibly negative effects on the perovskite based devices.…”