Controlling crystal growth in LDPs for solar cells
Controlling crystal growth alignment in low-dimensional perovskite (LDPs) for solar cells has been a persistent challenge, especially for low-n LDPs (n<3, n is the number of octahedral sheets) with wide band gaps (>1.7 eV) impeding charge flow.
In the paper 'Vertically-orientated low-dimensional perovskites for high-efficiency wide band gap perovskite solar cells' published in Nature Communications, the authors* explain how they overcame the transport limits by inducing vertical crystal growth through the addition of chlorine to the precursor solution.
They found that, in contrast to 3D halide perovskites (APbX3), the CI substituted I in the equatorial position of the unit cell, which induced a vertical strain in the perovskite octahedra, and was critical for initiating vertical growth. Atomistic modelling demonstrated the thermodynamic stability and miscibility of CI/I structures indicating the preferential arrangement for CI-incorporation at I-sites. Vertical alignment persisted at the solar cell level, which gave rise to a record 9.4% power conversion efficiency with a 1.4V open circuit voltage (the highest reported for a 2 eV wide band gap device).
This study demonstrates an atomic-level understanding of crystal tunability in low-n LDPs and unlocks new device possibilities for smart solar facades and indoor energy generation.
*Universita Degli Studi Di Pavia and INSTM (Italy) the Departments of Materials, and Physics (University of Oxford), King Abdullah University of Science & Technology and PSE (Saudi Arabia), Zernike Institute for Advanced Materials (The Netherlands), Centre for Convergent Technologies (Italy) and the Suzhou Institute of Nano-Tec and Nano-Bionics (China).
