Study on the defect density of states in light soaking effect enhanced performance of perovskite solar cells

Inorganic cesium lead halide perovskites, as alternative light absorbers for organic–inorganic hybrid perovskite solar cells, have attracted more and more attention due to their superb thermal stability for photovoltaic applications. However, the humid air instability of CsPbI2Br perovskite solar cells (PSCs) hinders their further development. The optoelectronic properties of CsPbI2Br films are closely related to the quality of films, so preparing high-quality perovskite films is crucial for fabricating high-performance PSCs. For the first time, we demonstrate that the regulation of ambient temperature of the dry air in the glovebox is able to control the growth of CsPbI2Br crystals and further optimize the morphology of CsPbI2Br film. Through controlling the ambient air temperature assisted crystallization, high-quality CsPbI2Br films are obtained, with advantages such as larger crystalline grains, negligible crystal boundaries, absence of pinholes, lower defect density, and faster carrier mobility. Accordingly, the PSCs based on as-prepared CsPbI2Br film achieve a power conversion efficiency of 15.5% (the maximum stabilized power output of 15.02%). Moreover, the optimized CsPbI2Br films show excellent robustness against moisture and oxygen and maintain the photovoltaic dark phase after 3 h aging in an air atmosphere at room temperature and 35% relative humidity (R.H.). In comparison, the pristine films are completely converted to the yellow phase in 1.5 h.

Download Full-text

An antibonding valence band maximum enables defect-tolerant and stable GeSe photovoltaics

Nature Communications ◽

10.1038/s41467-021-20955-5 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Shun-Chang Liu ◽

Chen-Min Dai ◽

Yimeng Min ◽

Yi Hou ◽

Andrew H. Proppe ◽

...

Keyword(s):

Solar Cells ◽

Valence Band ◽

Surface Passivation ◽

Defect Density ◽

Perovskite Solar Cells ◽

Valence Band Maximum ◽

Ambient Conditions ◽

Band Maximum ◽

Point Tracking ◽

Power Point

AbstractIn lead–halide perovskites, antibonding states at the valence band maximum (VBM)—the result of Pb 6s-I 5p coupling—enable defect-tolerant properties; however, questions surrounding stability, and a reliance on lead, remain challenges for perovskite solar cells. Here, we report that binary GeSe has a perovskite-like antibonding VBM arising from Ge 4s-Se 4p coupling; and that it exhibits similarly shallow bulk defects combined with high stability. We find that the deep defect density in bulk GeSe is ~1012 cm−3. We devise therefore a surface passivation strategy, and find that the resulting GeSe solar cells achieve a certified power conversion efficiency of 5.2%, 3.7 times higher than the best previously-reported GeSe photovoltaics. Unencapsulated devices show no efficiency loss after 12 months of storage in ambient conditions; 1100 hours under maximum power point tracking; a total ultraviolet irradiation dosage of 15 kWh m−2; and 60 thermal cycles from −40 to 85 °C.

Download Full-text

Perovskite Solar cells - the Role of Ions, Density of States, and Device Structure

10.29363/nanoge.nipho.2019.020 ◽

2018 ◽

Author(s):

Nir Tessler ◽

Yana Vaynzof

Keyword(s):

Solar Cells ◽

Density Of States ◽

Perovskite Solar Cells ◽

Device Structure

Download Full-text

Perovskite Solar Cell design using Tin Halide and Cuprous Thiocyanate for Enhanced Efficiency

International Journal of Engineering and Advanced Technology - Regular Issue ◽

10.35940/ijeat.f8778.088619 ◽

2019 ◽

Vol 8 (6) ◽

pp. 2817-2825 ◽

Cited By ~ 1

Keyword(s):

Solar Cell ◽

Density Of States ◽

Defect Density ◽

Cell Structure ◽

Perovskite Solar Cells ◽

Visible Region ◽

Transparent Conductive Oxide ◽

Effective Density ◽

Solar Cell Structure ◽

Metal Back

Utilization of Tin Halide as an absorber in Perovskite solar cells is immensely recognized as a substitute of lead halide absorber because of lead material’s toxicity. Also, Tin halide based Perovskites possess a potential for higher quantum efficiency because of their enhanced light absorption capability due to the wide-ranging absorption spectrum in the visible region with a comparatively lower bandgap of 1.3 eV than lead-based Perovskites. In the present work, glass/ transparent conductive oxide (TCO)/ titanium dioxide (buffer)/ tin halide Perovskite (Absorber)/ cuprous thiocyanate (HTM)/ Metal back solar cell structure has been designed and simulated by SCAPS software which yields Power Conversion Efficiency (PCE) of 28.32% and Fill Factor (FF) of 85.17%. The effect of total defect density, thickness, Valance Band Effective Density of States (VBEDS) and Conduction Band Effective Density of States (CBEDS) for an absorber layer has been analyzed. It has been observed that VBEDS variation has achieved PCE and FF to a significant extent i.e. up to 32.47% PCE and 85.86% FF

Download Full-text

Computational Study of Inverted All-Inorganic Perovskite Solar Cells Based on CsPbIxBr3-X Absorber Layer with Band Gap of 1.78 eV

10.26434/chemrxiv.13382069.v1 ◽

2020 ◽

Author(s):

Nahuel Martínez ◽

Carlos Pinzón ◽

Guillermo Casas ◽

Fernando Alvira ◽

Marcelo Cappelletti

Keyword(s):

Solar Cells ◽

Band Gap ◽

High Efficiency ◽

Defect Density ◽

Computational Study ◽

Perovskite Solar Cells ◽

Absorber Layer ◽

Inorganic Materials ◽

Tandem Solar Cells ◽

Inorganic Perovskite

All-inorganic perovskite solar cells (PSCs) with inverted p-i-n configuration have not yet reached the high efficiency achieved in the normal n-i-p architecture. However, the inverted all-inorganic PSC are more compatible with the fabrication of tandem solar cells. In this work, a theoretical study of all-inorganic PSCs with inverted structure ITO/HTL/CsPbIxBr3−x/ETL/Ag, has been performed by means of computer simulation. Four p‐type inorganic materials (NiO, Cu2O, CuSCN and CuI) and three n-type inorganic materials (ZnO, TiO2 and SnO2) were used as hole and electron transport layers (HTL and ETL), respectively. A band gap of 1.78 eV was used for the CsPbI x Br3−x perovskite layer. The simulation results allow identifying that CuI and ZnO are the most appropriate materials as HTL and ETL, respectively. Additionally, optimized values of thickness, acceptor density and defect density in the absorber layer have been obtained for the ITO/CuI/CsPbI x Br3−x /ZnO/Ag, from which, an optimum efficiency of 21.82% was achieved. These promising theoretical results aim to improve the manufacturing process of inverted all-inorganic PSCs and to enhance the performance of perovskite–perovskite tandem solar cells.

Download Full-text

Binary synergetic ions reduce defect density in ambient air processed perovskite solar cells

Solar Energy ◽

10.1016/j.solener.2020.01.069 ◽

2020 ◽

Vol 198 ◽

pp. 335-342

Author(s):

Hongyu Liu ◽

Peng Zhang ◽

Fei Wang ◽

Chong Jia ◽

Yiqing Chen

Keyword(s):

Solar Cells ◽

Defect Density ◽

Perovskite Solar Cells ◽

Ambient Air

Download Full-text

Improving Two-Step Prepared CH3NH3PbI3 Perovskite Solar Cells by Co-Doping Potassium Halide and Water in PbI2 Layer

Nanomaterials ◽

10.3390/nano9050666 ◽

2019 ◽

Vol 9 (5) ◽

pp. 666 ◽

Cited By ~ 6

Author(s):

Hsuan-Ta Wu ◽

Yu-Ting Cheng ◽

Ching-Chich Leu ◽

Shih-Hsiung Wu ◽

Chuan-Feng Shih

Keyword(s):

Solar Cells ◽

Power Conversion Efficiency ◽

Conversion Efficiency ◽

Defect Density ◽

Power Conversion ◽

Perovskite Solar Cells ◽

Organic Halide ◽

Co Doping ◽

Halide Perovskite ◽

Potassium Halides

Incorporating additives into organic halide perovskite solar cells is the typical approach to improve power conversion efficiency. In this paper, a methyl-ammonium lead iodide (CH3NH3PbI3, MAPbI3) organic perovskite film was fabricated using a two-step sequential process on top of the poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) hole-transporting layer. Experimentally, water and potassium halides (KCl, KBr, and KI) were incorporated into the PbI2 precursor solution. With only 2 vol% water, the cell efficiency was effectively improved. Without water, the addition of all of the three potassium halides unanimously degraded the performance of the solar cells, although the crystallinity was improved. Co-doping with KI and water showed a pronounced improvement in crystallinity and the elimination of carrier traps, yielding a power conversion efficiency (PCE) of 13.9%, which was approximately 60% higher than the pristine reference cell. The effect of metal halide and water co-doping in the PbI2 layer on the performance of organic perovskite solar cells was studied. Raman and Fourier transform infrared spectroscopies indicated that a PbI2-dimethylformamide-water related adduct was formed upon co-doping. Photoluminescence enhancement was observed due to the co-doping of KI and water, indicating the defect density was reduced. Finally, the co-doping process was recommended for developing high-performance organic halide perovskite solar cells.

Download Full-text