| Autor: |
Clark PCJ; Department of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Manchester M13 9PL, UK. pcjclark@gmail.com., Lewis NK; Department of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Manchester M13 9PL, UK. pcjclark@gmail.com., Ke JC; Department of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Manchester M13 9PL, UK. pcjclark@gmail.com., Ahumada-Lazo R; Department of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Manchester M13 9PL, UK. pcjclark@gmail.com., Chen Q; Department of Materials, The University of Manchester, Manchester M13 9PL, UK., Neo DCJ; Department of Chemistry, University of California, Irvine, Irvine, California 92697, USA., Gaulding EA; National Renewable Energy Laboratory, Golden, CO 80401, USA., Pach GF; National Renewable Energy Laboratory, Golden, CO 80401, USA., Pis I; Laboratorio TASC, IOM CNR, S.S. 14 km 163.5, 34149 Basovizza, Trieste, Italy.; Elettra-Sincrotrone Trieste S.C.p.A., S. S. 14 Km 163.5, 34149 Basovizza, Trieste, Italy., Silly MG; Synchrotron SOLEIL, BP 48, Saint-Aubin, F91192 Gif sur Yvette CEDEX, France., Flavell WR; Department of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Manchester M13 9PL, UK. pcjclark@gmail.com. |
| Abstrakt: |
Band bending in colloidal quantum dot (CQD) solids has become important in driving charge carriers through devices. This is typically a result of band alignments at junctions in the device. Whether band bending is intrinsic to CQD solids, i.e. is band bending present at the surface-vacuum interface, has previously been unanswered. Here we use photoemission surface photovoltage measurements to show that depletion regions are present at the surface of n and p-type CQD solids with various ligand treatments (EDT, MPA, PbI 2 , MAI/PbI 2 ). Using laser-pump photoemission-probe time-resolved measurements, we show that the timescale of carrier dynamics in the surface of CQD solids can vary over at least 6 orders of magnitude, with the fastest dynamics on the order of microseconds in PbS-MAI/PbI 2 solids and on the order of seconds for PbS-MPA and PbS-PbI 2 . By investigating the surface chemistry of the solids, we find a correlation between the carrier dynamics timescales and the presence of oxygen contaminants, which we suggest are responsible for the slower dynamics due to deep trap formation. |
