AI Article Synopsis
- Perovskite CHNHPbI has impressive photovoltaic performance, but there is limited understanding of its atomic movements, which are crucial for its transport properties.
- The research employs advanced neutron scattering techniques to create a detailed model of atomic dynamics involving molecular rotations and phonons over a broad energy range.
- The study finds that molecular dipoles become disordered at around 165 K, affecting thermal transport, and identifies that acoustic phonons, not optical ones, primarily drive thermal transport due to their shorter lifetimes.
Article Abstract
Perovskite CHNHPbI exhibits outstanding photovoltaic performances, but the understanding of the atomic motions remains inadequate even though they take a fundamental role in transport properties. Here, we present a complete atomic dynamic picture consisting of molecular jumping rotational modes and phonons, which is established by carrying out high-resolution time-of-flight quasi-elastic and inelastic neutron scattering measurements in a wide energy window ranging from 0.0036 to 54 meV on a large single crystal sample, respectively. The ultrafast orientational disorder of molecular dipoles, activated at ∼165 K, acts as an additional scattering source for optical phonons as well as for charge carriers. It is revealed that acoustic phonons dominate the thermal transport, rather than optical phonons due to sub-picosecond lifetimes. These microscopic insights provide a solid standing point, on which perovskite solar cells can be understood more accurately and their performances are perhaps further optimized.
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Source |
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5497077 | PMC |
| http://dx.doi.org/10.1038/ncomms16086 | DOI Listing |
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