Charge carrier localised in zero-dimensional (CH3NH3)3Bi2I9 clusters

Chengsheng Ni,Calum Mcdonald,Darragh Carolan,Paul Edwards,Paul Maguire,Vladimir Svrcek,Julia Payne,Davide Mariotti,Lethy Krishnan Jagadamma,Gordon Hedley,Gunisha Jain,John Irvine,Robert Martin,Ifor Samuel

doi:10.1038/s41467-017-00261-9

Abstract

A metal-organic hybrid perovskite (CH3NH3PbI3) with three-dimensional framework of metal-halide octahedra has been reported as a low-cost, solution-processable absorber for a thin-film solar cell with a power-conversion efficiency over 20%. Low-dimensional layered perovskites with metal halide slabs separated by the insulating organic layers are reported to show higher stability, but the efficiencies of the solar cells are limited by the confinement of excitons. In order to explore the confinement and transport of excitons in zero-dimensional metal–organic hybrid materials, a highly orientated film of (CH3NH3)3Bi2I9 with nanometre-sized core clusters of Bi2I93− surrounded by insulating CH3NH3+ was prepared via solution processing. The (CH3NH3)3Bi2I9 film shows highly anisotropic photoluminescence emission and excitation due to the large proportion of localised excitons coupled with delocalised excitons from intercluster energy transfer. The abrupt increase in photoluminescence quantum yield at excitation energy above twice band gap could indicate a quantum cutting due to the low dimensionality.

Highlights

A metal-organic hybrid perovskite (CH3NH3PbI3) with three-dimensional framework of metal-halide octahedra has been reported as a low-cost, solution-processable absorber for a thin-film solar cell with a power-conversion efficiency over 20%
As a collateral effect of this confinement of charge carriers in the atom-scale slab that increases the exciton recombination, the low-dimensional layered perovskites with layered corner-sharing (BX6)4− separated by organic cations have been reported to show structural relaxation and high luminescence when the thickness is decreased to few unit cells[6]
The materials show bhieoxcatgaohneadlrasyomrm(eBtriy2I9()P3−c6lu3/smtersm c) are and the face-shared BiI6 separated by CH3NH3+

Summary

Introduction

A metal-organic hybrid perovskite (CH3NH3PbI3) with three-dimensional framework of metal-halide octahedra has been reported as a low-cost, solution-processable absorber for a thin-film solar cell with a power-conversion efficiency over 20%. Low-dimensional layered perovskites with metal halide slabs separated by the insulating organic layers are reported to show higher stability, but the efficiencies of the solar cells are limited by the confinement of excitons. QDs of Si and PbS can efficiently generate multiple excitons from one high-energy absorbed photon following a mechanism known as carrier multiplication (CM) owing to their discrete energy levels and enhanced Coulomb interactions[12,13,14]. This is one of the suggested phenomena that may allow the efficiency of a single-junction solar cell to exceed the Shockley–Queisser limit[15]

Methods

Results

Conclusion