Berlin 2018 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 61: Focus: Fundamental Physics of Perovskites II - organized by Lukas Schmidt-Mende and Vladimir Dyakonov

CPP 61.4: Vortrag

Donnerstag, 15. März 2018, 10:30–10:45, C 130

Passivating perovskite surfaces by mixtures of PEDOT and dopant-free Spiro-OMeTAD — •L. Kegelmann¹, C. M. Wolff², J. A. Márquez Prieto¹, P. Tockhorn¹, T. Unold¹, D. Neher², B. Rech¹, and S. Albrecht¹ — ¹Helmholtz-Zentrum Berlin, Berlin, Germany — ²University of Potsdam, Institute of Physics and Astronomy, Potsdam, Germany

Perovskite solar cells have achieved efficiencies above 22% within few years. By now, the device parameter with the largest potential for further improvements is the open circuit voltage (Voc), which is mainly limited by recombination losses at the interfaces. Here, a poly(3,4-ethylenedioxythiophene) (PEDOT) layer doped with sulfonated copolymers is utilized as a hole selective contact (HSC) on top of perovskite absorbers. Transient photoluminescence (PL) and steady-state PL quantum yield measurements reveal longer charge carrier lifetimes and larger quasi-fermi level splitting for perovskite films after the PEDOT is deposited. PEDOT thin films therefore seem to suppress charge carrier recombination at the perovskite surface. By blending undoped Spiro-OMeTAD into the PEDOT dispersion, the surface energetics of the resulting films are shifted to larger ionisation energies as measured by photoelectron spectroscopy and the quasi-fermi level splitting is further enhanced. As a result, perovskite solar cells with mixtures of PEDOT and Spiro-OMeTAD as HSC achieve high Voc values above 1.15 V and stabilized efficiencies over 16%. This exceeds the Voc of reference devices with either doped Spiro-OMeTAD or pure PEDOT as HSC.