it's really depend on how do you want your HTM to be (in term of thickness, your time, environmental condition during your fabrication) for your solar cell. Do you use glovebox for your solar cell fabrication? well, what can I say is, 1st method seems to be fit when you are working outside of glove box and your HTM would be thicker (considering your spin speed is the same for method 2). Please be aware that you need some more time for your spiro to be fully oxidised.  Method 2 is seemed to be fits many application and work best when using glovebox and need shorter time to fully oxidised when comparing to 1st method. I always use anhydrous CBZ to be in safe side as water can cause your spiro solution to be cloudy hence changing its optoelectronic properties. higher LiTFSI salt can cause higher Jsc but somehow will decrease your Voc.

Dear Muhamad Zulhasif bin Mokhtar sir..

very thankful for your information.

Method-2

2,2ˊ,7,7ˊ-tetrakis(N,N-di-p-methoxyphenylamine)-9,9-spirobifluorene (spiro-OMeTAD, Merck, 72.3 mg) in anhydrous chlorobenzene (CB, 99.8%,

Sigma–Aldrich, 1.0 mL) containing 28.8 μL of 4-tert-butylpyridine (Aldrich) and 17.5 μL of lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) solution (520 mg Li-TFSI in 1 mL acetonitrile, Sigma–Aldrich).

I can confirm you about method#2 just with Spiro_OMeTAD :80mg,

But you need to check at different rpm in air (e.g 4000, 5000)

if you feel at 5000 rpm you have better efficiency then dilute solution with CB and reduce rpm up to 2000 - 4000rpm

after spin-coating HTL in air dont keep samples in glove-box just keep in air with cover for overnihgt.

i hope it will help you to optimize the HTL condition.

 Dear Muhammad Jahandar sir.

very thankful for your information.

i Hope it will work for my device.

Dear Muhammad Jahandar, if I spincoat the Spiro using your mentioned method in glovebox, would I need to leave it in glovebox or in air (covered) afterward?

Dear Rohit,

You may refer these two papers to improve your experiment technique.

Good luck

Article Incorporation of rubidium cations into perovskite solar cell...

Article Efficient and stable solution-processed planar perovskite so...

I case of Spiro-OMeTAD HTM, the aging treatment is needed after you deposited the Spiro layers around 10 hours before depositing metal electrode. In my case, air exposure overnight is better.

Hope this helps you.

Muhamad Zulhasif bin Mokhtar Hope you are good, I have little question why we dissolve Spiro in CB as CB is antisolvent, it means we don't dissolve Spiro, Can you please define chemistry behind this

Thanks