  Halide perovskites perform remarkably in optoelectronic devices including
tandem photovoltaics. However, this exceptional performance is striking given
that perovskites exhibit deep charge carrier traps and spatial compositional
and structural heterogeneity, all of which should be detrimental to
performance. Here, we resolve this long-standing paradox by providing a global
visualisation of the nanoscale chemical, structural and optoelectronic
landscape in halide perovskite devices, made possible through the development
of a new suite of correlative, multimodal microscopy measurements combining
quantitative optical spectroscopic techniques and synchrotron nanoprobe
measurements. We show that compositional disorder dominates the optoelectronic
response, while nanoscale strain variations even of large magnitude (~1 %) have
only a weak influence. Nanoscale compositional gradients drive carrier
funneling onto local regions associated with low electronic disorder, drawing
carrier recombination away from trap clusters associated with electronic
disorder and leading to high local photoluminescence quantum efficiency. These
measurements reveal a global picture of the competitive nanoscale landscape,
which endows enhanced defect tolerance in devices through spatial chemical
disorder that outcompetes both electronic and structural disorder.

Applied Physics;Materials Science;Optics