Characterization of perovskite systems: understanding and improving the performance and stability of photovoltaic devices
Description
In the past few years, hybrid perovskite solar cells have attracted a considerable amount of research and have undergone rapid development as next generation photovoltaics. The power conversion efficiency has then been rapidly increasing and has recently exceeded 25%. This class of materials has interesting optoelectronic properties such as a high optical absorption, a large diffusion length of the charge carriers as well as a low manufacturing cost. Nevertheless, there are several challenges that need to be addressed before commercialization will be possible, most significantly the long-term stability. In this thesis work, the main goal is to understand and improve the performance and stability under illumination of N-I-P perovskite-based solar cells. A detailed study of the reference system using CH3NH3PbI3 perovskite (MAPI) is presented by studying the formation mechanism of MAPI and its thermal behavior after annealing by XRD techniques. It showed that MAI and PbCl2 precursors initially form a MAPbCl3 layer, which transforms to MAPbI3 in an anion exchange reaction during thermal annealing, inducing a high level of strain in the MAPI layers. Solar cells were aged under continuous illumination (1 sun/35 C) and showed severe efficiency loss. The origin of devices instability under illumination were investigated in depth thanks to the differential aging. It consists in aging the different layers under illumination before the deposition of top layers in order to determine the key parameter (layer or interface) responsible of this degradation. Results have shown that for long time scales, the upper layers (P-layer and gold electrode are responsible of solar cells degradation, while the N layer/MAPI interface causes degradation at the first hundred hours. To get further insight into the role of ETL/MAPI interface on device behavior; advanced characterization methods, combining XPS and ToFSIMS, were developed and made it possible to study the degradation of the stack glass/ITO/N layer/MAPI, aged under illumination. Improved system with double cations perovskite Cs0.05FA0.95Pb (I 0.83Br0.17)3 have also been studied and show better stability under illumination of complete cells. (author)
Abstract (French)
Au cours des dernieres annees, les cellules solaires a base de perovskites hybrides ont attire considerablement l'attention. Des lors, grace aux travaux de recherche intensifs deployes, les efficacites de ces cellules ont tres rapidement evolue pour atteindre recemment un record de 25,2 %. Le caractere hybride (organique et inorganique) confere a cette classe de materiaux des proprietes optoelectroniques interessantes, telles qu'une forte absorption optique, une grande longueur de diffusion des porteurs de charge ainsi que la facilite de mise en solution et de fabrication a faible cout. Neanmoins, parmi les defis qui restent a relever pour l'industrialisation de cette technologie, le probleme de stabilite a long terme est sans doute l'un des principaux. Le but principal de ce travail de these est la comprehension et l'amelioration de la stabilite sous illumination des cellules solaires a base de perovskite et, plus particulierement, celles avec une architecture dite N-I-P (structure verre/ITO / Couche N / Perovskite / Couche P/ Electrode d'or) a base de perovskite CH3NH3PbI3 (MAPI). Au prealable des etudes de vieillissement, une etude DRX in situ detaillee de l'empilement verre /ITO /SnO2 /MAPI revele le mecanisme de formation de la MAPI, preparee a partir du PbCl2 et MAI en solution, a partir d'une perovskite chloree MAPbCl3 par echange ionique Cl/I.L'etude en temperature de la MAPI a montre un haut niveau de contraintes presents dans ces couches minces, qui se traduit par un taux eleve de deformation par rapport a la poudre de MAPI.La stabilite sous illumination des dispositifs de ce systeme de reference a ete etudiee et montre une importante perte d'efficacite des cellules completes. Afin de comprendre l'origine de cette instabilite, une methode de vieillissement differentiel a ete mise au point et consiste a faire vieillir les differentes couches de l'empilement de la cellule separement pour identifier la couche ou l'interface a l'origine de la degradation sous illumination. Ces vieillissements ont montre que la raison de degradation des cellules completes, sur les longues echelles de temps, est causee par les couches au-dessus de la MAPI (couche P et electrode d'or). L'interface couche N / MAPI a ete identifiee comme premiere cause d'instabilite (les premieres centaines d'heures) sous illumination et sa degradation a ete etudiee grace aux methodes de caracterisations combinees XPS et ToFSIMS. Finalement, un systeme optimise plus performant a base de perovskite double cations FACsPbIBr a montre une meilleure stabilite sous illumination des cellules completes
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Additional details
Additional titles
- Original title (French)
- Cellules solaires a base de materiaux perovskites: de la caracterisation des materiaux a l'amelioration des rendements et de la stabilite
Publishing Information
- Imprint Pagination
- 255 p.
- Report number
- FRCEA-TH--13467
INIS
- Country of Publication
- France
- Country of Input or Organization
- France
- INIS RN
- 53020236
- Subject category
- S36: MATERIALS SCIENCE; S14: SOLAR ENERGY;
- Resource subtype / Literary indicator
- Thesis
- Descriptors DEI
- AGING; ANNEALING; EFFICIENCY; PEROVSKITES; SOLAR CELLS; STABILITY; STRAINS; X-RAY DIFFRACTION; X-RAY PHOTOELECTRON SPECTROSCOPY
- Descriptors DEC
- COHERENT SCATTERING; DIFFRACTION; DIRECT ENERGY CONVERTERS; ELECTRON SPECTROSCOPY; EQUIPMENT; HEAT TREATMENTS; MINERALS; PHOTOELECTRIC CELLS; PHOTOELECTRON SPECTROSCOPY; PHOTOVOLTAIC CELLS; SCATTERING; SOLAR EQUIPMENT; SPECTROSCOPY
Optional Information
- Notes
- 154 refs.; Available from the INIS Liaison Officer for France, see the INIS website for current contact and E-mail addresses