Vacuum‐based deposition of optoelectronic thin films has a long‐standing history. However, in the field of perovskite‐based photovoltaics, these techniques are still not as advanced as their ...solution‐based counterparts. Although high‐efficiency vacuum‐based perovskite solar cells reaching power conversion efficiencies (PCEs) above 20% are reported, the number of studies on the underlying physical and chemical mechanism of the co‐evaporation of lead iodide and methylammonium iodide is low. In this study, the impact of one of the most crucial process parameters in vacuum processes—the substrate material—is studied. It is shown that not only the morphology of the co‐evaporated perovskite thin films is significantly influenced by the surface polarity of the substrate material, but also the incorporation of the organic compound into the perovskite framework. Based on these studies, a selection guide for suitable substrate materials for efficient co‐evaporated perovskite thin films is derived. This selection guide points out that the organic vacuum‐processable hole transport material 2,2″,7,7″‐tetra(N,N‐di‐p‐tolyl)amino‐9,9‐spirobifluorene is an ideal candidate for the fabrication of efficient all‐evaporated perovskite solar cells, demonstrating PCEs above 19%. Furthermore, building on the insights into the formation of the perovskite thin films on different substrate materials, a basic crystallization model for co‐evaporated perovskite thin films is suggested.
The suitability of substrate materials for co‐evaporated perovskite solar cells is commonly assessed via heuristic approaches. Here, a universal guideline for the choice of substrate material is developed by investigating the thin‐film formation of co‐evaporated perovskite absorbers on various substrate materials. The guideline enables a targeted screening of substrate materials based on their surface characteristics enabling efficient all‐evaporated perovskite solar cells.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
High‐quality charge carrier transport materials are of key importance for stable and efficient perovskite‐based photovoltaics. This work reports on electron‐beam‐evaporated nickel oxide (NiOx) ...layers, resulting in stable power conversion efficiencies (PCEs) of up to 18.5% when integrated into solar cells employing inkjet‐printed perovskite absorbers. By adding oxygen as a process gas and optimizing the layer thickness, transparent and efficient NiOx hole transport layers (HTLs) are fabricated, exhibiting an average absorptance of only 1%. The versatility of the material is demonstrated for different absorber compositions and deposition techniques. As another highlight of this work, all‐evaporated perovskite solar cells employing an inorganic NiOx HTL are presented, achieving stable PCEs of up to 15.4%. Along with good PCEs, devices with electron‐beam‐evaporated NiOx show improved stability under realistic operating conditions with negligible degradation after 40 h of maximum power point tracking at 75 °C. Additionally, a strong improvement in device stability under ultraviolet radiation is found if compared to conventional perovskite solar cell architectures employing other metal oxide charge transport layers (e.g., titanium dioxide). Finally, an all‐evaporated perovskite solar mini‐module with a NiOx HTL is presented, reaching a PCE of 12.4% on an active device area of 2.3 cm2.
A highly transparent nickel oxide hole transport layer prepared by oxygen‐assisted electron beam evaporation for perovskite‐based photovoltaics is reported. Using these layers in perovskite solar cells, efficient devices with stable power conversion efficiencies up to 18.5% for inkjet‐printed absorbers and 15.4% for co‐evaporated absorbers are demonstrated. In addition, good stability at elevated temperature and under ultraviolet radiation is shown.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
4.
CIGS absorbers and processes Niki, Shigeru; Contreras, Miguel; Repins, Ingrid ...
Progress in photovoltaics,
September 2010, Volume:
18, Issue:
6
Journal Article
We report on the analytical description of high-efficiency Cu(In,Ga)Se2-based solar cells produced with a static coevaporation process. We discuss classic quality markers such as grain morphology, ...composition, vertical compositional gradings, and grain orientation in these cells. We then describe the successful transfer of such results to industrially relevant inline processes in our module production line. Finally, we explicate one of the many optimisation routes for the further improvement of these Cu(In,Ga)Se2-based solar cells: Zn(O,S) buffer layers.
•Quality markers of high-efficiency Cu(In,Ga)Se2 (CIGS) cells re-examined.•Efficiency development of CIGS modules.•Zn(O,S) alternative buffer optimization.•Technology transfer from lab to industry
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Tin‐based perovskites are promising alternative absorber materials for lead‐free perovskite solar cells but need strategies to avoid fast tin (Sn) oxidation. Generally, this reaction can be slowed ...down by the addition of tin fluoride (SnF2) to the perovskite precursor solution, which also improves the perovskite layer morphology. Here, this work analyzes the spatial distribution of the additive within formamidinium tin triiodide (FASnI3) films deposited on top of poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hole transporting layers. Employing time‐of‐flight secondary ion mass spectrometry and a combination of hard and soft X‐ray photoelectron spectroscopy, it is found that SnF2 preferably accumulates at the PEDOT:PSS/perovskite interface, accompanied by the formation of an ultrathin SnS interlayer with an effective thickness of ≈1.2 nm.
The impact of the commonly used tin fluoride (SnF2) additive in Sn‐based perovskite solar cells on the poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/perovskite interface are analyzed. SnF2 is found to preferably precipitate at this interface where it forms a SnS interlayer of approximately 1.2 nm thickness induced by a chemical reaction with sulfur‐containing groups at the PEDOT:PSS surface.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Perovskite/CuIn1 − xGaxSe2 (CIGS) tandem photovoltaics (PV) promises high power conversion efficiencies in combination with the advantages of a light weight and an all thin‐film PV technology. ...However, the complexity of perovskite/CIGS tandem solar module architectures requires careful optimization of the layer stack under realistic solar irradiation conditions. Here, we provide a systematic numerical study on the energy yield (EY) of perovskite/CIGS tandem solar modules, optimizing the device architecture with regard to irradiance in various climate zones. In particular, variations of the spectral irradiation and the average photon energy are of decisive importance for the location‐specific optimization of the device architecture. Compared with the reference single‐junction CIGS thin‐film PV technology, we demonstrate a strong improvement in EY (>30%) in perovskite/CIGS thin‐film PV for perovskites of a wide range of bandgaps (1.55 ‐ 2.0 eV), reaching up to 52% improvement in EY for the optimal bandgap (around 1.8 eV). Of the two most favored architectures, the two‐terminal and four‐terminal devices, perovskite/CIGS tandem solar modules with low bandgap (∼1.55 eV) perovskite absorbers in the four‐terminal architecture outperform those in the two‐terminal architecture in average by 3.5% relative. However, for wide perovskite bandgaps ranging from 1.75 eV to 1.85 eV, both architectures perform comparably. The improvements in EY for perovskite/CIGS tandem solar modules highlight the potential of this technology but also the vital need for light management in tandem photovoltaics.
Energy yield (EY) modelling enables systematic optimizations of the architecture of perovskite/CIGS tandem solar modules with regard to realistic irradiation conditions. Variations of spectral irradiation and the average photon energy are of decisive importance for a location‐specific optimization of the architecture. Compared to a reference single‐junction CIGS solar module, the EY of perovskite/CIGS tandem PV for perovskites of a wide range of bandgaps (1.55 ‐ 2.0 eV) improves significantly by up to 52% for an optimal bandgap of around 1.8eV.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
In this article, we discuss the leading thin-film photovoltaic (PV) technology based on the Cu(In,Ga)Se2 (CIGS) compound semiconductor. This contribution includes a general comparison with the ...conventional Si-wafer-based PV technology and discusses the basics of the CIGS technology as well as advances in world-record-level conversion efficiency, production, applications, stability, and future developments with respect to a flexible product. Once in large-scale mass production, the CIGS technology has the highest potential of all PV technologies for cost-efficient clean energy generation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
A holistic simulation of a photovoltaic system requires multiple physical levels - the optoelectronic behavior of the semiconductor devices, the conduction of the generated current, and the ...actual operating conditions, which rarely correspond to the standard testing conditions (STC) employed in product qualification. We present a holistic simulation approach for all thin-film photovoltaic module technologies that includes a transfer-matrix method, a drift-diffusion model to account for the p-n junction, and a quasi-three-dimensional finite-element Poisson solver to consider electrical transport. The evolved digital model enables bidirectional calculation from material parameters to non-STC energy yield and vice versa, as well as accurate predictions of module behavior, time-dependent top-down loss analyses and bottom-up sensitivity analyses. Simple input data like current-voltage curves and material parameters of semiconducting and transport layers enables fitting of otherwise less-defined values. The simulation is valuable for effective optimizations, but also for revealing values for difficult-to-measure parameters.
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