Ulatowski Aleksander M, Wright Adam D, Wenger Bernard, Buizza Leonardo R V, Motti Silvia G, Eggimann Hannah J, Savill Kimberley J, Borchert Juliane, Snaith Henry J, Johnston Michael B, Herz Laura M
Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom.
J Phys Chem Lett. 2020 May 7;11(9):3681-3688. doi: 10.1021/acs.jpclett.0c01048. Epub 2020 Apr 27.
Successful chemical doping of metal halide perovskites with small amounts of heterovalent metals has attracted recent research attention because of its potential to improve long-term material stability and tune absorption spectra. However, some additives have been observed to impact negatively on optoelectronic properties, highlighting the importance of understanding charge-carrier behavior in doped metal halide perovskites. Here, we present an investigation of charge-carrier trapping and conduction in films of MAPbBr perovskite chemically doped with bismuth. We find that the addition of bismuth has no effect on either the band gap or exciton binding energy of the MAPbBr host. However, we observe a substantial enhancement of electron-trapping defects upon bismuth doping, which results in an ultrafast charge-carrier decay component, enhanced infrared emission, and a notable decrease of charge-carrier mobility. We propose that such defects arise from the current approach to Bi-doping through addition of BiBr, which may enhance the presence of bromide interstitials.
用少量异价金属对金属卤化物钙钛矿进行成功的化学掺杂，因其具有改善材料长期稳定性和调节吸收光谱的潜力，近来受到了研究关注。然而，已观察到一些添加剂会对光电性能产生负面影响，这凸显了理解掺杂金属卤化物钙钛矿中电荷载流子行为的重要性。在此，我们展示了对化学掺杂铋的MAPbBr钙钛矿薄膜中电荷载流子俘获和传导的研究。我们发现，铋的添加对MAPbBr主体的带隙或激子结合能均无影响。然而，我们观察到铋掺杂后电子俘获缺陷大幅增加，这导致了超快的电荷载流子衰减成分、增强的红外发射以及电荷载流子迁移率显著降低。我们认为，此类缺陷源于当前通过添加BiBr进行铋掺杂的方法，这可能会增加溴间隙原子的存在。
