l*****l
发帖数: 85 | 1 I have tried to follow Sargent group's procedure to make a thin film out of
PbS quantum dot. I spin-coated a film from a 150 mg/ml octane solution of
butylamine-capped PbS QDs. The spinning condition was 500 rpm for 60 seconds
. But the film qaulity was terrible. It was obviously not uniform at all.
Could anyone share some experiences in thin film fabrication with QDs? What
are the tricks?
Thank you. |
l*******s
发帖数: 65 | 2 you may want to contact the authors, they can give you some tricks. |
t***3
发帖数: 100 | 3 Actually the film should be very smooth and shinny. Several tips that
might be helpful for you:
1) Stay in glovebox, otherwise PbS nanodots are oxidized very fast and
then you would see white waxy stuff on the film;
2) Make sure the butylamine ligand exchange is complete; if you have too
many oleic acid leftovers, the film would be terrible.
Hopefully it helps and good luck to you!
|
l*****l
发帖数: 85 | 4 Thank both lenovodos and tj403 for the kind replies.
The problem actually is that both oleic acid-capped PbS and butylamine
exchanged PbS form small aggregates in octane. I expected those QDs can
completely dissolve in octance. But it did not happen. The films I got were
continous but with many tiny domains of aggregates.
I did everything from washing to exchange to spin coat in air. But with OA
the capping reagent, the QDs shoudl be readily dissolve/disperse in a
nonpolar solvent even PbO forms
【在 t***3 的大作中提到】
: Actually the film should be very smooth and shinny. Several tips that
: might be helpful for you:
: 1) Stay in glovebox, otherwise PbS nanodots are oxidized very fast and
: then you would see white waxy stuff on the film;
: 2) Make sure the butylamine ligand exchange is complete; if you have too
: many oleic acid leftovers, the film would be terrible.
: Hopefully it helps and good luck to you!
:
|
t***3
发帖数: 100 | 5 You are welcome. Actually, we are always using octane and producing nice
shinny films. For any aggregate problem, i suggest you centrifugate the
solution at >10000rpm for 3min before film fabrication. |
l*****l
发帖数: 85 | 6 Thank you again for your information.
I guess the problem may be because of the quantum dot preparation. I will
try to centrifuge the octance solution before spin coating.
By the way, what is the concentration you used?
Thank you.
【在 t***3 的大作中提到】
: You are welcome. Actually, we are always using octane and producing nice
: shinny films. For any aggregate problem, i suggest you centrifugate the
: solution at >10000rpm for 3min before film fabrication.
|
t***3
发帖数: 100 | 7 For 500 rpm, ～ 200nm film, 150mg/ml in OCT.
Hehe, one question, what is the PCE do you get now? |
l*****l
发帖数: 85 | 8 very low.
i guess it is < 0.06% at 0.1 sun condition |
t***3
发帖数: 100 | 9 That is not surprising. However, you could make it much much better through
systematic optimization. |
l*****l
发帖数: 85 | 10 For some reason, I always had small aggregates even in the OA-PbS octane
solution. I expects that all QDs are capped with oleic acid. The capped PbS
should be easily dissolved in a non-polar solvent. There should not be any
aggregates. I can not explain why they were formed.
For the butylamine-exchanged QDs, there were even much more aggregates. I
feel that the QDs spacing have been reduced too much after exchanged with BA
. I guess there is some trick to control the exchange extent, but could n
【在 t***3 的大作中提到】
: That is not surprising. However, you could make it much much better through
: systematic optimization.
|
t***3
发帖数: 100 | 11 For synthesis, use PbO and technical grade oleic acid; depend on the size,
you should choose methanol or acetone to wash it; for BA exchange, do it in
glove box; tune the duration of BA treatment time (monitor the blue shift of
absorption) to control the exchange; there is a optimum duration. Carefully
reading all publications from Nozik and Sargent's group. |
