Perovskite surface treatment with additives has been reported to improve charge extraction, stability, and/or surface passivation. In this study, treatment of a 3D perovskite ((FAPbI 3 ) 1−x (MAPbBr 3 ) x ) layer with a thienothiophene-based organic cation (TTMAI), synthesized in this work, is investigated. Detailed analyses reveal that a 2D (n = 1) or quasi-2D layer does not form on the PbI 2rich surface 3D perovskite. TTMAI-treated 3D perovskite solar cells (PSCs) fabricated in this study show improved fill factors, providing an increase in their power conversion efficiencies (PCEs) from 17% to over 20%. It is demonstrated that the enhancement is due to better hole extraction by drift-diffusion simulations. Furthermore, thanks to the hydrophobic nature of the TTMAI, PSC maintains 82% of its initial PCE under 15% humidity for over 380 h (the reference retains 38%). Additionally, semitransparent cells are demonstrated reaching 17.9% PCE with treated 3D perovskite, which is one of the highest reported efficiencies for double cationic 3D perovskites. Moreover, the semitransparent 3D PSC (TTMAI-treated) maintains 87% of its initial efficiency for six weeks (>1000 h) when kept in the dark at room temperature. These results clearly show that this study fills a critical void in perovskite research where highly efficient and stable semitransparent perovskite solar cells are scarce.
Deposition of functionalized nanoparticles onto solid surfaces has created a new revolution in electronic devices. Surface adsorbates such as ionic surfactants or additives are often used to stabilize such nanoparticle suspensions; however, little is presently known about the influence of such surfactants and additives on specific electronic and chemical functionality of nanoparticulate electronic devices. This work combines experimental measurements and theoretical models to probe the role of an ionic surfactant in the fundamental physical chemistry and electronic charge carrier behavior of photodiode devices prepared using multicomponent organic electronic nanoparticles. A large capacitance was detected, which could be subsequently manipulated using the external stimuli of light, temperature, and electric fields. It was demonstrated that analyzing this capacitance through the framework of classical semiconductor analysis produced substantially misleading information on the electronic trap density of the nanoparticles. Electrochemical impedance measurements demonstrated that it is actually the stabilizing surfactant that creates capacitance through two distinct mechanisms, each of which influenced charge carrier behavior differently. The first mechanism involved a dipole layer created at the contact interfaces by mobile ions, a mechanism that could be replicated by addition of ions to solution-cast devices and was shown to be the major origin of restricted electronic performance. The second mechanism consisted of immobile ionic shells around individual nanoparticles and was shown to have a minor impact on device performance as it could be removed upon addition of electronic charge in the photodiodes through either illumination or external bias. The results confirmed that the surfactant ions do not create a significantly increased level of charge carrier traps as has been previously suspected, but rather, preventing the diffusion of mobile ions through the nanoparticulate film and their accumulation at contacts is critical to optimize the performance.
Controlling the phenomenological morphology effects on the performance of the perovskite solar cell (PSC) is a continuing concern due to its photo-physical complexity and the existing contrary reports. Distinguishing the effect of the formed electron and hole traps in the bulk and at surface/interfaces of the perovskite layer from their impact on the performance of the device can be beneficial in optimizing fabrication methods. Here, the transient AC and steady state DC measurements, and morphology characterizations confirm the variation of performance parameters with respect to grain boundaries growth. The device physics is uncovered with respect to the grain size (GS) of the perovskite layer employing the theoretical drift-diffusion framework incorporating the electronic and ionic contributions. The increase of open circuit voltage (V oc ) for devices with large GS can be associated to the density of defect states. The findings here suggest a more pronounced role of interfaces in efficiency enhancement of the PSCs with the emphasis on the impact of the hole transport layer (HTL)/ perovskite layer interface which is also found to be accountable to the difference between the device internal voltage and the terminal voltage and minimizing this difference can lead to an enhancement of approximately 100 mV in V oc . Additionally, the electron traps in the bulk of the perovskite layer play a distinguishable role in the reduction of V oc for the device with the smallest GS. The ionic defect density is also estimated. Considering our results and previous reports, the performance of the PSC is remarkably dependent on the method of fabrication and the associated perovskite conversion mechanism, and not necessarily on GS. The results are expected to deliver important guidelines for the development of more efficient PSCs by further enhancement of the V oc towards its thermodynamic limit of 1.32V, via creating optimal interfaces.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.