期刊
ADVANCED FUNCTIONAL MATERIALS
卷 30, 期 13, 页码 -出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/adfm.201909983
关键词
bismuth-based solar absorbers; defect tolerance; perovskite-inspired materials; photoinduced current transient spectroscopy; photovoltaics
类别
资金
- EPSRC Centre for Doctoral Training in Graphene Technology [EP/L016087/1]
- Aziz Foundation
- EPSRC Centre for Doctoral Training in New and Sustainable Photovoltaics
- EPSRC Centre for Doctoral Training in Nanoscience and Nanotechnology [EP/L015978/1]
- EPSRC [EP/P027032/1, EP/L011700/1, EP/N004272/10]
- Isaac Newton Trust
- Winton Programme for the Physics of Sustainability
- DFG Emmy Noether Programme
- National Natural Science Foundation of China [61750110517, 61950410759, 61805166]
- Jiangsu Province Natural Science Foundation [BK20170345]
- Collaborative Innovation Center of Suzhou Nano Science Technology
- Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
- 111 Project
- Joint International Research Laboratory of Carbon-Based Functional Materials and Devices
- Royal Academy of Engineering [RF\ 201718\1701]
- Kim and Juliana Silverman Research Fellowship at Downing College, Cambridge
- EPSRC Department Training Partnership studentship [EP/N509620/1]
- EPSRC [EP/P027032/1, EP/L011700/1, EP/N004272/1] Funding Source: UKRI
In the search for nontoxic alternatives to lead-halide perovskites, bismuth oxyiodide (BiOI) has emerged as a promising contender. BiOI is air-stable for over three months, demonstrates promising early-stage photovoltaic performance and, importantly, is predicted from calculations to tolerate vacancy and antisite defects. Here, whether BiOI tolerates point defects is experimentally investigated. BiOI thin films are annealed at a low temperature of 100 degrees C under vacuum (25 Pa absolute pressure). There is a relative reduction in the surface atomic fraction of iodine by over 40%, reduction in the surface bismuth fraction by over 5%, and an increase in the surface oxygen fraction by over 45%. Unexpectedly, the Bi 4f(7/2) core level position, Fermi level position, and valence band density of states of BiOI are not significantly changed. Further, the charge-carrier lifetime, photoluminescence intensity, and the performance of the vacuum-annealed BiOI films in solar cells remain unchanged. The results show BiOI to be electronically and optoelectronically robust to percent-level changes in surface composition. However, from photoinduced current transient spectroscopy measurements, it is found that the as-grown BiOI films have deep traps located approximate to 0.3 and 0.6 eV from the band edge. These traps limit the charge-carrier lifetimes of BiOI, and future improvements in the performance of BiOI photovoltaics will need to focus on identifying their origin. Nevertheless, these deep traps are three to four orders of magnitude less concentrated than the surface point defects induced through vacuum annealing. The charge-carrier lifetimes of the BiOI films are also orders of magnitude longer than if these surface defects were recombination active. This work therefore shows BiOI to be robust against processing conditions that lead to percent-level iodine-, bismuth-, and oxygen-related surface defects. This will simplify and reduce the cost of fabricating BiOI-based electronic devices, and stands in contrast to the defect-sensitivity of traditional covalent semiconductors.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据