TY - JOUR
T1 - A Highly Emissive Surface Layer in Mixed-Halide Multication Perovskites
AU - Andaji-Garmaroudi, Zahra
AU - Abdi-Jalebi, Mojtaba
AU - Guo, Dengyang
AU - Macpherson, Stuart
AU - Sadhanala, Aditya
AU - Tennyson, Elizabeth M.
AU - Ruggeri, Edoardo
AU - Anaya, Miguel
AU - Savenije, Tom J.
AU - More Authors, null
PY - 2019
Y1 - 2019
N2 - Mixed-halide lead perovskites have attracted significant attention in the field of photovoltaics and other optoelectronic applications due to their promising bandgap tunability and device performance. Here, the changes in photoluminescence and photoconductance of solution-processed triple-cation mixed-halide (Cs0.06MA0.15FA0.79)Pb(Br0.4I0.6)3 perovskite films (MA: methylammonium, FA: formamidinium) are studied under solar-equivalent illumination. It is found that the illumination leads to localized surface sites of iodide-rich perovskite intermixed with passivating PbI2 material. Time- and spectrally resolved photoluminescence measurements reveal that photoexcited charges efficiently transfer to the passivated iodide-rich perovskite surface layer, leading to high local carrier densities on these sites. The carriers on this surface layer therefore recombine with a high radiative efficiency, with the photoluminescence quantum efficiency of the film under solar excitation densities increasing from 3% to over 45%. At higher excitation densities, nonradiative Auger recombination starts to dominate due to the extremely high concentration of charges on the surface layer. This work reveals new insight into phase segregation of mixed-halide mixed-cation perovskites, as well as routes to highly luminescent films by controlling charge density and transfer in novel device structures.
AB - Mixed-halide lead perovskites have attracted significant attention in the field of photovoltaics and other optoelectronic applications due to their promising bandgap tunability and device performance. Here, the changes in photoluminescence and photoconductance of solution-processed triple-cation mixed-halide (Cs0.06MA0.15FA0.79)Pb(Br0.4I0.6)3 perovskite films (MA: methylammonium, FA: formamidinium) are studied under solar-equivalent illumination. It is found that the illumination leads to localized surface sites of iodide-rich perovskite intermixed with passivating PbI2 material. Time- and spectrally resolved photoluminescence measurements reveal that photoexcited charges efficiently transfer to the passivated iodide-rich perovskite surface layer, leading to high local carrier densities on these sites. The carriers on this surface layer therefore recombine with a high radiative efficiency, with the photoluminescence quantum efficiency of the film under solar excitation densities increasing from 3% to over 45%. At higher excitation densities, nonradiative Auger recombination starts to dominate due to the extremely high concentration of charges on the surface layer. This work reveals new insight into phase segregation of mixed-halide mixed-cation perovskites, as well as routes to highly luminescent films by controlling charge density and transfer in novel device structures.
KW - halide perovskites
KW - luminescence
KW - passivation
KW - photoinduced ion migration
KW - time-resolved spectroscopy
UR - http://www.scopus.com/inward/record.url?scp=85071891546&partnerID=8YFLogxK
U2 - 10.1002/adma.201902374
DO - 10.1002/adma.201902374
M3 - Article
AN - SCOPUS:85071891546
SN - 0935-9648
VL - 31
JO - Advanced Materials
JF - Advanced Materials
IS - 42
M1 - 1902374
ER -