Dowtherm a

Silver nitrate, 3-mercaptopropionic acid, ethylene glycol, silver diethyldithiocarbamate [Ag(DDTC)], 1-dodecanethiol, (3-aminopropyl)trimethoxysilane (APTMS), tetraethyl orthosilicate (TEOS), and Dowtherm A were purchased from Sigma-Aldrich (St. Louis, MO), 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide hydrochloride(EDC) and N-hydroxysulfosuccinimide(sulfo-NHS) were purchased from Thermo Fisher Scientific (Rockford, IL), and all of the amino acids were purchased from Novabiochem (Philadelphia, PA).

Bulk CsPbBr₃ (0.02 g,
0.035 mmol, prepared as described
above) was loaded into a zirconia bowl with 25 zirconia balls (4 mm
and 5 mm) and with OAmBr (0.01 g, 0.03 mmol, prepared as described
above), and 0.4 mL of mesitylene (98%, Sigma-Aldrich). Another tested
ligand system was a mixture of OA (0.05 mL, Sigma-Aldrich, 90%) and
OLA (0.05 mL, Strem, 95%). Other tested solvents were octadecene (Sigma-Aldrich,
90%), Dowtherm A (diphyl, eutectic mixture of 26% diphenyl + 73.5%
dipheniloxide), toluene (Sigma-Aldrich, 99.5%), hexane (>95%, Sigma-Aldrich),
and chloroform (HPLC grade, Fisher Chemicals). The bowl was mounted
on a planetary ball mill (Fritsch, Pulverisette 7, classic line),
and the speed was set to 500 rpm. The time was varied from 30 min
to 24 h. After the milling, a bright green suspension was obtained,
which was diluted with toluene (2 mL) and used as-obtained or precipitated
one time with acetonitrile (0.5 mL, 99.8%, Aldrich). The precipitate
was redispersed in 2 mL of toluene.
Alternatively, CsBr (0.011
g, 0.05 mmol, Aldrich, 99.9%) and PbBr₂ (0.018 g, 0.05
mmol) were loaded into a zirconia bowl with 25 zirconia balls (4 mm
and 5 mm) and with 1.6 mL of mesitylene and 0.01 g of OAmBr (0.03
mmol). The subsequent milling lasted 2 h at 500 rpm. The bright green
crude solution was diluted with 2 mL of toluene.