000261333 001__ 261333
000261333 005__ 20190509131804.0
000261333 0247_ $$2doi$$a10.5075/epfl-thesis-9071
000261333 037__ $$aTHESIS
000261333 041__ $$aeng
000261333 088__ $$a9071
000261333 245__ $$aComposition and Interface Engineering of Organic-Inorganic Hybrid Perovskites to Improve Photovoltaic Performance and Stability
000261333 260__ $$c2018$$bEPFL$$aLausanne
000261333 269__ $$a2018
000261333 300__ $$a163
000261333 336__ $$aTheses
000261333 502__ $$aProf. Paul Joseph Dyson (président) ; Prof. Mohammad Khaja Nazeeruddin, Prof. Michael Graetzel (directeurs) ; Prof. MAJED CHERGUI, Prof. Emilio Palomares, Prof. Shahzada Ahmad (rapporteurs)
000261333 520__ $$aFaced with the growing demands for energy in modern society, organic-inorganic metal halide perovskite materials have recently fascinated the photovoltaics (PV) research community due to a combination of their high quality optoelectronic properties and their ease in the fabrication proceed. As a result, solar cells employing the perovskite materials have been researched exponentially on their way and now the power conversion efficiency (PCE) of perovskite solar cells have been improved over 23% since the first report showing the PCE of 3% in 2009.
In this thesis, I investigate compositional modification of perovskite materials and optimization of the charge transporting materials to produce high efficiency, stable and reproducible perovskite solar cells. First of all, after the reasonable performance was achieved, we have innovated a new approach of interface engineering in a perovskite layer to boost efficiency of devices. Engineering a compositional gradient with formamidinium bromide (FABr) at the rear interface between a pristine mixed perovskite ((FAPbI3)0.85(MAPbBr3)0.15) film and a hole transporting material (spiro-OMeTAD) demonstrated that charge collection is improved and charge recombination is reduced at the interface, which leads to a striking enhancement in open-circuit voltage (VOC). This result shed light on the importance of the passivation engineering on the rear surface of perovskite layers.
However, beyond the improvement of efficiency, a long-term stability under moisture and continuous illumination is still remained as another challenge for market deployment of the perovskite solar cells. To develop the stability, we have developed the engineering by the surface growth of a two-dimensional (2D) perovskite, the crystal structure of A2BX4, on top of a bulk three-dimensional (3D) perovskite ABX3 film. It is well-known that the 2D perovskite has the superior stability, but suffered because of their low efficiency in the application of photovoltaics. The formation of a distinct 2D perovskite on top of the 3D perovskite (Cs0.1FA0.74MA0.13PbI2.48Br0.39) layer was proved by investigation of structural and optical properties of the stack. This embodying two different type of perovskite layer in one film had never been shown. Finally, this innovative approach led to the PCE of 21% and enhanced stability sustaining 85% of the initial value after 800 hours under full illumination. Thus, my approach of coating 2D perovskite layer make the perovskite solar cells more effective and stable for commercialization.
Besides, to avoid the toxic chemical the lead free perovskite (Cs2AgBiBr6) was explored as photovoltaics and the further improvement can be expected. The last results presented in this thesis are related to optimization of the electron transporting layer (ETL) and hole-transporting materials (HTM) for efficient perovskite solar cells. It is shown that the ETL and the HTMs are playing a significant role in realizing efficient and stable perovskite solar cells.
000261333 592__ $$b2018
000261333 6531_ $$aPerovskites
000261333 6531_ $$aSolar cell
000261333 6531_ $$aOptimization
000261333 6531_ $$aMixed perovskite
000261333 6531_ $$aPassivation
000261333 6531_ $$aLow dimensional perovskite
000261333 6531_ $$aStability
000261333 6531_ $$aLead-free perovskite
000261333 6531_ $$aHole transporting materials
000261333 6531_ $$aMetal oxide conductive layer
000261333 700__ $$0248328$$aCho, Kyung Taek$$g243815
000261333 720_2 $$aNazeeruddin, Mohammad Khaja$$edir.$$g105958
000261333 720_2 $$aGraetzel, Michael$$edir.$$g105292
000261333 8564_ $$uhttps://infoscience.epfl.ch/record/261333/files/EPFL_TH9071.pdf$$s11973779
000261333 909C0 $$pLPI
000261333 909CO $$pthesis$$pDOI$$pSB$$ooai:infoscience.epfl.ch:261333$$qGLOBAL_SET
000261333 918__ $$aSB$$cISIC$$dEDCH
000261333 919__ $$aLPI
000261333 920__ $$a2018-11-30$$b2018
000261333 970__ $$a9071/THESES
000261333 973__ $$sPUBLISHED$$aEPFL
000261333 980__ $$aTHESIS