Thin‐film solar cells are made by vapor deposition of Earth‐abundant materials: tin, zinc, oxygen and sulfur. These solar cells had previously achieved an efficiency of about 2%, less than 1/10 of ...their theoretical potential. Loss mechanisms are systematically investigated and mitigated in solar cells based on p‐type tin monosulfide, SnS, absorber layers combined with n‐type zinc oxysulfide, Zn(O,S) layers that selectively transmit electrons, but block holes. Recombination at grain boundaries is reduced by annealing the SnS films in H2S to form larger grains with fewer grain boundaries. Recombination near the p‐SnS/n‐Zn(O,S) junction is reduced by inserting a few monolayers of SnO2 between these layers. Recombination at the junction is also reduced by adjusting the conduction band offset by tuning the composition of the Zn(O,S), and by reducing its free electron concentration with nitrogen doping. The resulting cells have an efficiency over 4.4%, which is more than twice as large as the highest efficiency obtained previously by solar cells using SnS absorber layers.
Solar cells are made by vapor deposition of Earth‐abundant materials, i.e., p‐type tin monosulfide (SnS) absorber layers with surfaces passivated by tin dioxide (SnO2) covered by n‐type nitrogen‐doped zinc oxysulfide (Zn(O,S):N) buffer layers. The cells show energy conversion efficiencies over 4.4%, which is more than twice as large as the highest efficiency obtained previously by solar cells using SnS absorber layers.
A path to 10% efficiency for tin sulfide devices Mangan, Niall M.; Brandt, Riley E.; Steinmann, Vera ...
2014 IEEE 40th Photovoltaic Specialist Conference (PVSC),
2014-June
Conference Proceeding
We preform device simulations of a tin sulfide (SnS) device stack using SCAPS to define a path to 10% efficient devices. We determine and constrain a baseline device model using recent experimental ...results on one of our 3.9% efficient cells. Through a multistep fitting process, we find a conduction band cliff of -0.2 eV between SnS and Zn(O,S) to be limiting the open circuit voltage (V OC ). To move towards a higher efficiency, we can optimize the buffer layer band alignment. Improvement of the SnS lifetime to >1 ns is necessary to reach 10% efficiency. Additionally, absorber-buffer interface recombination must be suppressed, either by reducing recombination activity of defects or creating a strong inversion layer at the interface.
Tin sulfide (SnS), as a promising absorber material in thin‐film photovoltaic devices, is described. Here, it is confirmed that SnS evaporates congruently, which provides facile composition control ...akin to cadmium telluride. A SnS heterojunction solar cell is demons trated, which has a power conversion efficiency of 3.88% (certified), and an empirical loss analysis is presented to guide further performance improvements.
Tin sulfide is regarded as a possible earth-abundant alternative for chalcogenide thin film photovoltaics. The material has strong absorption in the visible wavelength region and the possibility for ...high carrier mobility. We review recent progress for SnS solar cell efficiencies. Annealing in H 2 S gas and surface passivation of SnS are thought to be two key components that increase efficiency of SnS devices. An efficiency of η = 3.88% 1 was achieved via thermal evaporation, a manufacturing-friendly deposition method.
(Sn,Al)O x composite films with various aluminum (Al) to tin (Sn) ratios were deposited using an atomic layer deposition technique. The chemisorption behavior of cyclic amide of tin(II) and ...trimethylaluminum were analyzed by Rutherford backscattering spectroscopy. Both precursors showed retarded and enhanced chemisorption on Al2O3 and SnO2 surfaces, respectively. The films show highly anisotropic electrical conductivity, i.e., much higher resistivity in the direction through the film than parallel to the surface of the film. The cause of the anisotropy was investigated by cross-sectional transmission electron microscopy, which showed a nanolaminate structure of crystalline SnO2 grains separated by thin, amorphous Al2O3 monolayers. When the Al concentration was higher than ∼35 atom %, the composite films became amorphous, and the vertical and lateral direction resistivity values converged toward one value. By properly choosing the ratio of SnO2 and Al2O3 subcycles, controlled adjustment of film electrical resistivity over more than 15 orders of magnitude was successfully demonstrated.
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