We present solution-based fabrication and characterization of the lead-free perovskite-related methylammonium antimony iodide (CH 3 NH 3 ) 3 Sb 2 I 9 compound. By photothermal deflection spectroscopy (PDS), we determined a peak absorption coefficient α ≈ 10 5 cm −1 and an optical band gap of 2.14 eV for amorphous films of (CH 3 NH 3 ) 3 Sb 2 I 9 . Compared to the related Bi compound, the Sb-perovskite shows no exciton peak in its absorption spectrum. The photoluminescence emission (PL) is observed at 1.58 eV, and the Urbach tail energy of this amorphous compound is E u = 62 meV, indicating a substantial amount of energetic disorder. We fabricate a planar heterojunction solar cell with a (CH 3 NH 3 ) 3 Sb 2 I 9 absorber layer that yields a power conversion efficiency of η ≈ 0.5%, already featuring a decent fill factor (FF) of 55% and open-circuit voltage of 890 mV but low photocurrent densities. The result of this basic study on (CH 3 NH 3 ) 3 Sb 2 I 9 shows that this compound is a possible starting point for further research into Sb-based lead-free perovskite solar cells.L ead-based organic−inorganic hybrid semiconductors like CH 3 NH 3 PbI 3 (MAPI) have shown high potential as efficient absorber materials for single-junction solar cells due to their outstanding optoelectronic properties 1 and the easy and cheap fabrication methods. The power conversion efficiencies of these three-dimensional (3D) perovskite solar cells have increased rapidly up to more than 22% in 2016 2−5 after only 6 years of research starting from the first reported perovskite solar cell with an efficiency of 3.8%. 6 However, the low chemical stability of this lead-based perovskite under ambient air and the toxicity of the heavy metal lead could be obstacles for commercialization. 6−11 The tin analogous perovskite compound CH 3 NH 3 SnI 3 has exhibited moderate conversion efficiencies of up to 6% but is even more unstable under air and moisture because of the rapid oxidation of the Sn 2+ state to the Sn 4+ state. 12−14 Another promising group of materials for lead-free alternatives are the zero-dimensional (0D) Biperovskites A 3 Bi 2 X 9 (e.g., A = Cs + , MA + ; X = I − , Br − ). 15−17 These materials show high band gaps of E g > 1.8 eV, 18,19 which are suitable for tandem or triple solar cells. 20,21 Bismuth is a nontoxic element, and the Bi-based perovskites showed a better chemical stability under ambient atmosphere than the MAPI perovskite. 22 However, the Bi-perovskites also show the signature of excitons in their absorption spectrum that have binding energies in the range of 400 meV. 19,22 This leads to relatively low short-circuit current densities due to insufficient exciton splitting and charge carrier extraction. Bi-perovskitebased solar cells exhibit conversion efficiencies of 1% 22 with a TiO x electron transport layer (ETL) and 0.1% 23 in planar devices with pin-architectures where the exciton splitting at the interfaces is even more critical.In this work, we present the exchange of bismuth by antimony, which is less toxic than P...
In recent years, efficiencies of bulk heterojunction solar cells have risen substantially mostly due to the development of well-absorbing small molecules that replace fullerenes as the acceptor molecule. The improved light absorption due to the combination of two strongly absorbing molecules raises the question, how to best combine the absorption onsets of the donor and acceptor molecule to maximize efficiency. By using numerical simulations, we explain under which circumstances complementary absorption or overlapping absorption bands of the two molecules will be more beneficial for efficiency. Only when mobility and lifetime of charge carriers are sufficiently high to allow sufficient charge collection for layer thicknesses around the second interference maximum, a combination of complementary absorbing molecules is more efficient. For smaller thicknesses, a blend of molecules with the same absorption onset achieves higher efficiencies.
The preparation of a printable silicon ink using semiconductor grade and commercially available trisilane (Si3H8) is reported. The synthesis is carried out in solution at room temperature or below in N2 atmosphere at ambient pressure and involves an initial sonication step, followed by irradiation with ultraviolet light. The production of higher order silanes via ultrasound is demonstrated using gas chromatography and nuclear magnetic resonance measurements are used to show that a combined sonophotolytic treatment yields a highly branched silicon hydride polymer. In addition, scanning electron microscopy (SEM) images are used to ascertain the sonocatalytic production of silicon nanoparticles. Furthermore, it is argued that these particles are partially responsible for enabling dramatically accelerated polymer growth, not otherwise observed in the same amount of time using ultraviolet light alone. Finally, the utility of the ink used in this study is demonstrated for the field of printable electronics by fabricating amorphous silicon thin films by spin‐coating and atmospheric pressure chemical vapor deposition with optoelectronic properties approaching those of state‐of‐the‐art plasma enhanced chemical vapor deposition (PECVD) material.
Hematite (α-Fe 2 O 3) is known for poor electronic transport properties, which are the main drawback of this material for optoelectronic applications. In this study, we investigate the concept of enhancing electrical conductivity by the introduction of oxygen vacancies during temperature treatment under low oxygen partial pressure. We demonstrate the possibility of tuning the conductivity continuously by more than five orders of magnitude during stepwise annealing in a moderate temperature range between 300 and 620 K. With thermoelectric power measurements, we are able to attribute the improvement of the electrical conductivity to an enhanced charge-carrier density by more than three orders of magnitude. We compare the oxygen vacancy doping of hematite thin films with hematite nanoparticle layers. Thereby we show that the dominant potential barrier that limits charge transport is either due to grain boundaries in hematite thin films or due to potential barriers that occur at the contact area between the nanoparticles, rather than the potential barrier within the small polaron hopping model, which is usually applied for hematite. Furthermore, we discuss the transition from oxygen-deficient hematite α-Fe 2 O 3−x towards the magnetite Fe 3 O 4 phase of iron oxide at high density of vacancies.
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.