Simple Method of Dual Passivation with Efficiency Beyond 20% for Fabricating Perovskite Solar Cells

[NNadir]

The paper to which I'll briefly refer in this post is this one: Simple Method of Dual Passivation with Efficiency Beyond 20% for Fabricating Perovskite Solar Cells in the Full Ambient Air (Tingting Zhong, Lei Shi, Huiying Hao, Jingjing Dong, Kunpeng Tang, Xiang Xu, Shindume Lomboleni Hamukwaya, Hao Liu, and Jie Xing ACS Sustainable Chemistry & Engineering 2021 9 (38), 13010-13020)

I really have not too much to say about lead perovskite solar cells except that I'm not quite sure "distributed" lead on rooves is a particularly good idea, but nobody cares what I say.

I thought I'd just reproduce, for fun, the "simple" method for the "simple" preparation of lead perovskite cells in air, from this paper:

Materials

The laser-patterned FTO (TEC-A7) glass substrate was purchased from Advanced Election Technology CO, Ltd. Titanium(IV)isopropoxide (99.999%), ammonium acetate (NH4Ac, 99.996%), ethanol (≥99.5%), dimethyl sulfoxide (DMSO, 99.8%), N,N-dimethylformamide (DMF, 99.8%), chlorobenzene (CB, 99.5%), acetonitrile (99.8%), and EA (99.8%) were purchased from Aladdin Corporation (Shanghai, China). TiO2 paste (Dyesol-30-NR-D) and PbI2 (99.999%) were obtained from Advanced Election Technology CO, Ltd. CH3NH3I (MAI, ≥99.5%), CH3(NH2)2I (FAI, ≥99.5%), CH3NH3Cl (MACl, ≥99.5%), phenethylammonium iodide (PEAI, ≥99.5%), Spiro-OMeTAD (≥99.5%), 4-terbutylpyridine (TBP, 96%), Li-TFSI (99%), and FK209 (99%) were purchased from Xi’an Polymer Light Technology Crop. (Xi’an, China).

Device Fabrication

FTO glass substrates were cleaned in the detergent, deionized water (DI water), ethanol, and isopropanol by a sequential ultrasonic cleaner and then dried in air. Further plasma cleaning was performed, and the substrate was treated with a power of 40 W for 3 min.
The 40 μL titanium(IV)isopropoxide and 8 μL concentrated hydrochloric acid were mixed in 1 mL ethanol to compound the compact TiO2 (C-TiO2). Then, FTO glass substrates were spin-coated at 3000 rpm for 30 s and annealed at 150 °C for 5 min on a hot plate. Then, the same process was repeated twice and annealed for 15 min. After that, the coated substrates were calcined at 500 °C for 30 min in the muffle furnace. Then, the coated substrates were immersed into a 40 mM TiCl4 aqueous solution for 30 min at 70 °C and calcined for 30 min at 500 °C in the muffle furnace to obtain a C-TiO2 layer. Mesoporous TiO2 (M-TiO2) precursor solution was obtained by mixing TiO2 paste with ethanol (weight ratio = 1:6). Then, the substrates were spin-coated at 4000 rpm for 30 s and annealed at 120 °C for 10 min on a hot plate, followed by sintering for 30 min at 500 °C in the muffle furnace. Then, they were immersed into a 40 mM TiCl4 aqueous solution for 30 min at 500 °C and calcined for 30 min at 500 °C.

The perovskite precursor solution (1.4 M) was obtained through the formula MA0.9FA0.1PbI3–xClx in the co-solvent (VDMSO/VDMF = 4:1). In addition, 50 μL of PEAI/DMF solution (100 mg/mL) was then added to the above precursor solution. NH4Ac was dissolved in EA with a concentration of 0.005, 0.01, and 0.1 mg/mL, respectively. The perovskite layer was spin-coated on the M-TiO2 layer at 1000 rpm for 10 s and 5000 rpm for 30 s continuously, and 100 μL of EA (with different concentrations of NH4Ac or without it) was dropped at the 10th second at 5000 rpm, followed by thermal annealing at 100 °C on the hot plate for 40 min.

The 91 mg of Spiro-OMeTAD, 22 μL of Li-TFSI (520 mg in 1 mL of acetonitrile), 18 μL of FK209 (375 mg in 1 mL of acetonitrile), and 36 μL of TBP were dissolved in 1 mL of chlorobenzene. Then, it was spin-coated at a speed of 4000 rpm for 20 s on the perovskite film. At last, a 100 nm-thick Ag electrode was thermally evaporated onto the stack. All the processes of fabrication were done in the full ambient air condition (30–40% RH).

The structure of spiro-OmeTAD:



Delicious chemistry I think. I'm sure the lead iodide in this process is very "green." Lots of heat, and lots of stuff obtained from petroleum, but very "green."

I just can't wait until they build giant reactors to manufacture this stuff on a thousands upon thousands of tons scale, can you? You can do it in the presence of air.

Green, very green and very "sustainable," do ya think?

[eppur_se_muova]

1. Who the heck introduced this usage ? VDMSO/VDMF 4:1

I know, it was probably nicely subscripted in the formatted paper -- but it plays merry hob with search engines. What was wrong w/ DMSO/DMF = 4:1 (v/v) ?

But first let's find alternatives to LEAD, hmmm ?

[NNadir]

2. I generally like subscripts except in the case in equations where there are...

...five or six of them in sequence reflecting obscure variables and/or index numbers.

There is a lot of stuff written about tin as an alternative to lead in perovskite solar cells, but personally, I couldn't care less. (Tin perovskite solar cells don't work quite as well as lead perovskite solar cells, but they are obviously less dangerous.)

To my mind we have already developed an alternative to solar cells that has superior environmental and thermodynamic properties owing to a vastly higher energy to mass ratio.

The real problem with nuclear energy to my mind is that some people are psychologically unprepared to understand that it makes the redundancy of so called "renewable energy" completely unnecessary. The required redundancy of dangerous fossil fuels wherever the application of the solar/wind fantasy is soaking up money, land, and material is already proving to be a disaster, first in Europe and soon in many parts of the United States.

I've been following the CAISO electrical grid supply and demand in California this month very closely, downloading spreadsheets and doing calculations. It's mind blowing how well the single Diablo Canyon plant does on a 12 acre footprint when compared to well over a thousand square miles of wind turbines. I may write about that in this space.

Shutting Diablo Canyon to placate a quasi-religious dogma about solar cells in my mind is a crime against humanity.