Dresden 2017 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 38: Fundamentals of Perovskite Photovoltaics V (joint session CPP/DS/HL)

CPP 38.9: Talk

Wednesday, March 22, 2017, 12:45–13:00, ZEU 250

Highly Stable and Efficient Perovskite Solar Cells via Multication Engineering — •Michael Saliba — EPFL, Lausanne, Switzerland

Perovskites have emerged as low-cost, high efficiency photovoltaics with certified efficiencies of 22.1%. The perovskites used for solar cells have an ABX3 structure where the cation A is methylammonium (MA), formamidinium (FA), or Cs; the metal B is Pb; and the halide X is Br or I. Unfortunately, single-cation perovskites often suffer from phase, temperature or humidity instabilities. This is particularly noteworthy for CsPbX3 and FAPbX3 showing a photoinactive yellow phase at room temperature instead of the more desired photoactive black phase.

Here, we investigate triple cation (with Cs, MA, FA) perovskites resulting in significantly improved reproducibality and stability. We then use multiple cation engineering as a strategy to integrate the seemingly too small Rb (that never shows a black phase as a single-cation perovskite) to study novel multication perovskites.

One composition containing Rb, Cs, MA and FA resulted in a stabilized efficiency of 21.6%. The open-circuit voltage of 1.24 volts at a band gap of 1.63 eV leads to a very small loss-in-potential of 0.39 V, versus 0.4 V for commercial silicon cells. Polymer-coated cells maintained 95% of their initial performance at 85°C for 500 hours under full solar illumination and maximum power point tracking.(1)

(1) Saliba et al., Incorporation of rubidium cations into perovskite solar cells improves photovoltaic performance. Science (2016).