Bromine in triple mesoscopic hole-conductor-free perovskite solar cells
Résumé
Within the challenging race for alternative energy sources, hybrid metal halide perovskite solar cells (PSCs) have undergone unprecedented progress with efficiencies reaching now 25.5% [1-3]. These remarkable performances result from the exceptional optoelectrical properties of hybrid perovskite materials. Coupled with their potential for low fabrication cost, perovskite solar cell technology is very promising. However, since hybrid halide perovskites have a highly ionic character, they can decompose under external stresses such as moisture, solvents and heating cycles [4-6]. Reducing environmental stresses imposed by moisture or oxygen for example, in order to improve the long-term stability of perovskite solar cells, is critical to the deployment of this technology.
In 2017, Grancini et al [7] published a structure proven to be stable for more than 10,000 hrs, measured uned controlled standard conditions, by engineering an ultra-stable 2D/3D (HOOC(CH2)4NH3)2PbI4/CH3NH3PbI3 perovskite junction. This structure is based on a fully printable architecture made of three mesoporous layers in which the perovskite is embed.
In this communication, we investigate the effects of changing the perovskite composition in this architecture by adding and/or replacing iodine with bromine into its chemical composition to tune device, increasing the band gap of the material [8], opening the gate to potential application in water splitting (VOC > 1.23 V at pH = 0 [9]). After characterization of their photovoltaic properties, the cells, reaching VOC ~1.3 V are studied by SEM coupled to EDX, XRD, Raman, absorption and photoluminescence spectroscopies.
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