Solvation of NiO _x for hole transport layer deposition in perovskite solar cells

Abstract

A series of nickel oxide (NiO x ) inks, in the perovskite antisolvent chlorobenzene (CB) containing 15% ethanol, were prepared for the fabrication of p-i-n perovskite solar cells by blade coating. The inks included triethylamine (Et3N) and alkyl xanthate salts as ligands to disperse NiO x particle aggregates and stabilize suspension. A total of four inks were evaluated: 0X (Et3N with no alkyl xanthate), 4X (Et3N + potassium n-butyl xanthate), 12X (Et3N + potassium n-dodecyl xanthate), and 18X (Et3N + potassium n-octadecyl xanthate). The inks were characterized by UV–visible spectroscopy and FT-IR spectroscopy and the resulting films analyzed by thermogravimetry and scanning electron microscopy. Devices prepared using the 0X ink resulted in a peak power conversion efficiency (PCE) of 14.47% (0.25 cm2) and 9.96% (1 cm2). The 0X devices showed no significant loss of PCE after 100 days in a nitrogen flow box. Devices prepared with inks containing alkyl xanthate ligand had lower PCE that decreased with decreasing chain length, 18X > 12X > 4X.

Recent Developments in Upscalable Printing Techniques for Perovskite Solar Cells

“…small molecules like Spiro-OMeTAD [119][120][121][122] and NiO x , [123][124][125] but also electron transport layers (ETLs) like the fullerenes C 60 , [112] PCBM, [112,124,126,127] ZnO, [128] SnO 2 , [129][130][131][132] and TiO 2 . [133] Recently, Lee et al developed a new donor-acceptor-donor type HTL with 4-dicyanomethylene-4H-cyclopenta[2,1-b;3,4b']dithiophene (diCN-CPDT) core tethered with two bis(alkoxy) diphenylaminocarbazole periphery groups (Figure 3b) and applied it for the fabrication of fully printed perovskite solar cell using a thermal assisted blade-coating technique.…”

“…[ 109 ] Apart from these physical and chemical modification approaches, several other approaches such as solvent engineering, adding, and doping strategies have also been summarized well in the previous reports. [ 24,113 ] Furthermore, several groups have successfully developed blade‐coating technique for printing of not only HTLs like the polymers PEDOT:PSS, [ 112,114–116 ] and PTAA [ 117,118 ] or small molecules like Spiro‐OMeTAD [ 119–122 ] and NiO x , [ 123–125 ] but also electron transport layers (ETLs) like the fullerenes C 60 , [ 112 ] PCBM, [ 112,124,126,127 ] ZnO, [ 128 ] SnO 2 , [ 129–132 ] and TiO 2 . [ 133 ] Recently, Lee et al.…”

Synthesizing and formulating metal oxide nanoparticle inks for perovskite solar cells

“…While effective at stabilizing our particles as dispersions in non-aqueous solvents, we were unable to produce functional devices of n–i–p configuration due to passivation of the PVSK surface that hindered charge extraction. 93 When deposited in the p–i–n configuration, device performances up to 14.47% PCE were obtained. Our current work is looking at further NiO x formulations with a focus on optimizing interfacial compatibility.…”

“…64,[94][95][96][97][98] While spin-coating is effective at forming uniform coatings, this method limits scalability and the results are often difficult to translate to larger area deposition methods. 46 Other methods being explored are spray pyrolysis, 76 blade/meniscus coating, 67,93,99 and slot die roll to roll. 100 Our work has been exclusively centered on blade coating films.…”