posted on 2021-09-22, 19:03authored byEssa A. Alharbi, Anurag Krishna, Thomas P. Baumeler, Mathias Dankl, George C. Fish, Felix Eickemeyer, Olivier Ouellette, Paramvir Ahlawat, Viktor Škorjanc, Elsa John, Bowen Yang, Lukas Pfeifer, Claudia Esther Avalos, Linfeng Pan, Mounir Mensi, Pascal Alexander Schouwink, Jacques-E. Moser, Anders Hagfeldt, Ursula Rothlisberger, Shaik M. Zakeeruddin, Michael Grätzel
The
defects present in metal halide perovskite are deleterious
to both the performance and stability of photovoltaic devices. Consequently,
there is an intense focus on developing defect mitigation strategies.
Herein we report a facile strategy that employs methylammonium triiodide
(MAI3) as an additive to the perovskite precursor solution.
We examine the effect of MAI3 on the structural and optoelectronic
properties by X-ray diffraction, density functional theory calculations,
molecular dynamics simulations, solid-state nuclear magnetic resonance,
steady-state, time-resolved photoluminescence (TRPL), and time-resolved
terahertz spectroscopy (TRTS). Specifically, TRPL and TRTS show that
MAI3 suppresses nonradiative recombination and increases
the charge carrier mobility. As a result, the champion device shows
a power conversion efficiency (PCE) of 23.46% with a high fill factor
of >80%. Furthermore, these devices exhibit enhanced operational
stability,
with the best device retaining ∼90% of its initial PCE under
1 sun illumination with maximum power point tracking for 350 h.