Large diffusion lengths of excitons in perovskite and TiO2 heterojunction

Abstract

Solar cells based on organometal halide perovskites have recently become very promising among other materials because of their cost-effective character and improvements in efficiency. Such performance is primarily associated with effective light absorption and large diffusion length of charge carriers. Our paper is devoted to the explanation of large diffusion lengths in these systems.The transport mean free path of charged carriers in a perovskite/TiO 2 heterojunction that is an important constituent of the solar cells have been analyzed. Large transport length is explained by the planar diffusion of indirect excitons. Diffusion length of the coupled system increases by several orders compared to single carrier length due to the correlated character of the effective field acting on the exciton.

Evaluation of Damage Coefficient for Minority-Carrier Diffusion Length of Triple-Cation Perovskite Solar Cells under 1 MeV Electron Irradiation for Space Applications

“…Organo-halide perovskite solar cells (PSCs) are attracting significant interest as the next generation of solar cells because of their lightweight, high power conversion efficiencies (PCE), and low cost. The perovskite material in PSCs has a high optical absorption coefficient α (5 × 10 –5 –5 × 10 –4 /cm), and its holes/electrons have minority-carrier diffusion lengths L exceeding 1 μm, , which is much longer than the thickness of the perovskite absorber layer (∼600 nm). Hence, PSCs can collect the photoproduction carriers quite efficiently.…”

Improved perovskite solar cell efficiency by tuning the colloidal size and free ion concentration in precursor solution using formic acid additive

“…The rapidly increased PCE is attributed to two important factors. Firstly the superior optoelectronic properties such as high carrier mobility [12][13][14][15][16] , long carrier lifetime [17,18] , high optical absorption coefficient across the entire visible spectrum [15,[19][20][21][22] , long carrier diffusion length [18,[23][24][25] , shallow defects [26] make the lead halide perovskites the best candidate not only for solar cells, but also for LEDs [27][28][29] , lasers [30][31][32] , and photodetectors [15,[33][34][35] . Secondly there have been dedicated effort s from a broad range of fields to optimize all components in the device, such as the electron transport layers [36][37][38][39][40] , hole transport layer [41,42] , cell structure design [43][44][45] , perovskite film deposition process [6,7,[46][47][48][49][50] , chemical composition…”

Determination of the complete set of optical parameters of micron-sized polycrystalline CH3NH3PbI3−xClx films from the oscillating transmittance and reflectance spectra

“…But, it should be noted that mixing of CH 3 NH 3 PbI 3 compound with other halogens (chlorine and bromine) leads to an increase of stability to degradation [11,12] and also affects significantly on the physical properties. For example, MAPbI 3−x Cl x films show suited bandgap (1.6 eV), long electron and hole diffusion lengths (>1 μm [13,14]), and therefore are in demand for solar cell applications.…”