Identifying the optimum thickness of electron transport layers for highly efficient perovskite planar solar cells

The fabrication of pinhole-free and compact electron transport layers is crucial for achieving high power conversion efficiency of perovskite solar cells. In this work, we report efficient perovskite solar cells using ultrathin TiO2 films (5–20 nm) as high-quality electron transport layers deposited by the atomic layer deposition technique. The as-prepared solar cells on FTO substrates show a high efficiency of 13.6%, employing the optimum 10 nm thick TiO2 layer. Furthermore, the flexible cells on PET substrates exhibit an efficiency of 7.2% with low-temperature-processed TiO2 layers at 80 °C. The effects of layer thicknesses on the cell performance are investigated to reveal the mechanism of high-performance, which is mainly attributed to high transmittance, low leakage current, and low charge transfer resistance and recombination rate. Our major findings are expected to provide a guide to design ultrathin compact electron transport layers for efficient perovskite solar cells.

[1]  H. Butt,et al.  Yttrium-substituted nanocrystalline TiO₂ photoanodes for perovskite based heterojunction solar cells. , 2014, Nanoscale.

[2]  Henk J. Bolink,et al.  Flexible high efficiency perovskite solar cells , 2014 .

[3]  Feng Huang,et al.  CH₃NH₃PbI₃-based planar solar cells with magnetron-sputtered nickel oxide. , 2014, ACS applied materials & interfaces.

[4]  Jeffrey A. Christians,et al.  An inorganic hole conductor for organo-lead halide perovskite solar cells. Improved hole conductivity with copper iodide. , 2014, Journal of the American Chemical Society.

[5]  Peng Gao,et al.  Effect of Annealing Temperature on Film Morphology of Organic–Inorganic Hybrid Pervoskite Solid‐State Solar Cells , 2014 .

[6]  Andrew C. Grimsdale,et al.  Perovskite-based solar cells: impact of morphology and device architecture on device performance , 2015 .

[7]  M. Topič,et al.  Optimal I-V Curve Scan Time of Solar Cells and Modules in Light of Irradiance Level , 2012 .

[8]  Bert Conings,et al.  Perovskite‐Based Hybrid Solar Cells Exceeding 10% Efficiency with High Reproducibility Using a Thin Film Sandwich Approach , 2014, Advanced materials.

[9]  Guangda Niu,et al.  Review of recent progress in chemical stability of perovskite solar cells , 2015 .

[10]  Alex K.-Y. Jen,et al.  High-performance perovskite-polymer hybrid solar cells via electronic coupling with fullerene monolayers. , 2013, Nano letters.

[11]  G. Cao,et al.  Effect of an Ultrathin TiO2 Layer Coated on Submicrometer‐Sized ZnO Nanocrystallite Aggregates by Atomic Layer Deposition on the Performance of Dye‐Sensitized Solar Cells , 2010, Advanced materials.

[12]  Qingfeng Dong,et al.  Electron-hole diffusion lengths > 175 μm in solution-grown CH3NH3PbI3 single crystals , 2015, Science.

[13]  Licheng Sun,et al.  Recent Progress on Hole‐Transporting Materials for Emerging Organometal Halide Perovskite Solar Cells , 2015 .

[14]  Anders Hagfeldt,et al.  Effect of Different Hole Transport Materials on Recombination in CH3NH3PbI3 Perovskite-Sensitized Mesoscopic Solar Cells. , 2013, The journal of physical chemistry letters.

[15]  Francisco Fabregat-Santiago,et al.  Role of the Selective Contacts in the Performance of Lead Halide Perovskite Solar Cells. , 2014, The journal of physical chemistry letters.

[16]  A. Di Carlo,et al.  Progress in flexible dye solar cell materials, processes and devices , 2014 .

[17]  J. Noh,et al.  Efficient inorganic–organic hybrid heterojunction solar cells containing perovskite compound and polymeric hole conductors , 2013, Nature Photonics.

[18]  Qi Chen,et al.  Low-temperature solution-processed perovskite solar cells with high efficiency and flexibility. , 2014, ACS nano.

[19]  Yang Yang,et al.  Interface engineering of highly efficient perovskite solar cells , 2014, Science.

[20]  H. Lee,et al.  Polyfluorene Derivatives are High‐Performance Organic Hole‐Transporting Materials for Inorganic−Organic Hybrid Perovskite Solar Cells , 2014 .

[21]  Hyun Suk Jung,et al.  Highly efficient and bending durable perovskite solar cells: toward a wearable power source , 2015 .

[22]  Alain Goriely,et al.  Morphological Control for High Performance, Solution‐Processed Planar Heterojunction Perovskite Solar Cells , 2014 .

[23]  M. Grätzel,et al.  Sequential deposition as a route to high-performance perovskite-sensitized solar cells , 2013, Nature.

[24]  Ningyi Yuan,et al.  The effect of ALD-Zno layers on the formation of CH₃NH₃PbI₃ with different perovskite precursors and sintering temperatures. , 2014, Chemical communications.

[25]  Juan Bisquert,et al.  Slow Dynamic Processes in Lead Halide Perovskite Solar Cells. Characteristic Times and Hysteresis. , 2014, The journal of physical chemistry letters.

[26]  S. Bent,et al.  Nanoengineering and interfacial engineering of photovoltaics by atomic layer deposition. , 2011, Nanoscale.

[27]  Peng Gao,et al.  Nanocrystalline rutile electron extraction layer enables low-temperature solution processed perovskite photovoltaics with 13.7% efficiency. , 2014, Nano letters.

[28]  M. Grätzel,et al.  Title: Long-Range Balanced Electron and Hole Transport Lengths in Organic-Inorganic CH3NH3PbI3 , 2017 .

[29]  C. Chang,et al.  Efficient and air-stable plastics-based polymer solar cells enabled by atomic layer deposition , 2011 .

[30]  Peng Gao,et al.  Impedance spectroscopic analysis of lead iodide perovskite-sensitized solid-state solar cells. , 2014, ACS nano.

[31]  J. Teuscher,et al.  Efficient Hybrid Solar Cells Based on Meso-Superstructured Organometal Halide Perovskites , 2012, Science.

[32]  Kun Zhang,et al.  Highly compact TiO2 layer for efficient hole-blocking in perovskite solar cells , 2014 .

[33]  Aldo Di Carlo,et al.  Flexible Perovskite Photovoltaic Modules and Solar Cells Based on Atomic Layer Deposited Compact Layers and UV‐Irradiated TiO2 Scaffolds on Plastic Substrates , 2015 .

[34]  Nripan Mathews,et al.  High efficiency electrospun TiO₂ nanofiber based hybrid organic-inorganic perovskite solar cell. , 2014, Nanoscale.

[35]  W. Daoud,et al.  Recent progress in organic–inorganic halide perovskite solar cells: mechanisms and material design , 2015 .

[36]  David Cahen,et al.  Elucidating the charge carrier separation and working mechanism of CH3NH3PbI3−xClx perovskite solar cells , 2014, Nature Communications.

[37]  Tsutomu Miyasaka,et al.  Organometal halide perovskites as visible-light sensitizers for photovoltaic cells. , 2009, Journal of the American Chemical Society.