Organic N‐Type Molecule: Managing the Electronic States of Bulk Perovskite for High‐Performance Photovoltaics

The power conversion efficiency (PCE) of planar p–i–n perovskite solar cells (pero‐SCs) is commonly lower than that of the n–i–p pero‐SCs, due to the severe nonradiative recombination stemming from the more p‐type perovskite with prevailing electron traps. Here, two n‐type organic molecules, DMBI‐2‐Th and DMBI‐2‐Th‐I, with hydrogen‐transfer properties for the doping of bulk perovskite aimed at regulating its electronic states are synthesized. The generated radicals in these n‐type dopants with high‐lying singly occupied molecular orbitals enable easy transfer of the thermally activated electrons to the MAPbI3 perovskite for the realization of n‐doped perovskites. The n‐doping degree could be further enhanced by using the iodine ionized dopant DMBI‐2‐Th‐I. The doping effect could reduce the electron trap density, increase the electron concentration of the bulk perovskite, and simultaneously improve the surface electronic contact. When the DMBI‐2‐Th‐I‐doped perovskite is used in planar p–i–n pero‐SCs, the nonradiative recombination is significantly suppressed. As a result, the photovoltaic performance improved significantly, as evidenced by an excellent PCE of 20.90% and a robust ambient stability even under high relative humidity. To the best of the knowledge, this work represents the first example where organic n‐type dopants are used to tune the electronic states of a bulk perovskite film for efficient planar p–i–n pero‐SCs.

[1]  Yang Yang,et al.  Multifunctional Fullerene Derivative for Interface Engineering in Perovskite Solar Cells. , 2015, Journal of the American Chemical Society.

[2]  H. Bolink,et al.  Trap‐Assisted Non‐Radiative Recombination in Organic–Inorganic Perovskite Solar Cells , 2015, Advanced materials.

[3]  Yanfa Yan,et al.  Predictions for p-Type CH3NH3PbI3 Perovskites , 2014 .

[4]  Rui Zhu,et al.  Enhanced photovoltage for inverted planar heterojunction perovskite solar cells , 2018, Science.

[5]  Meicheng Li,et al.  Highly Efficient Electron‐Selective Layer Free Perovskite Solar Cells by Constructing Effective p–n Heterojunction , 2017 .

[6]  Yanfa Yan,et al.  Unusual defect physics in CH3NH3PbI3 perovskite solar cell absorber , 2014 .

[7]  Yaowen Li,et al.  New Strategy for Two‐Step Sequential Deposition: Incorporation of Hydrophilic Fullerene in Second Precursor for High‐Performance p‐i‐n Planar Perovskite Solar Cells , 2018 .

[8]  Lei Meng,et al.  Recent Advances in the Inverted Planar Structure of Perovskite Solar Cells. , 2016, Accounts of chemical research.

[9]  Philip Schulz,et al.  Electronic Level Alignment in Inverted Organometal Perovskite Solar Cells , 2015 .

[10]  Zhenghong Lu,et al.  Managing grains and interfaces via ligand anchoring enables 22.3%-efficiency inverted perovskite solar cells , 2020 .

[11]  Yongli Gao,et al.  Qualifying composition dependent p and n self-doping in CH3NH3PbI3 , 2014 .

[12]  S. Fabiano,et al.  Enhanced n-Doping Efficiency of a Naphthalenediimide-Based Copolymer through Polar Side Chains for Organic Thermoelectrics , 2018, ACS energy letters.

[13]  Yanfa Yan,et al.  Progress in Theoretical Study of Metal Halide Perovskite Solar Cell Materials , 2017 .

[14]  Yang Yang,et al.  Constructive molecular configurations for surface-defect passivation of perovskite photovoltaics , 2019, Science.

[15]  Henry J. Snaith,et al.  Efficient planar heterojunction perovskite solar cells by vapour deposition , 2013, Nature.

[16]  Z. Bao,et al.  Mechanistic study on the solution-phase n-doping of 1,3-dimethyl-2-aryl-2,3-dihydro-1H-benzoimidazole derivatives. , 2013, Journal of the American Chemical Society.

[17]  Q. Gong,et al.  Inverted Perovskite Solar Cells: Progresses and Perspectives , 2016 .

[18]  O. Bakr,et al.  Metal-Doped Lead Halide Perovskites: Synthesis, Properties, and Optoelectronic Applications , 2018, Chemistry of Materials.

[19]  Liduo Wang,et al.  Efficient n-type dopants with extremely low doping ratios for high performance inverted perovskite solar cells , 2016 .

[20]  Yongfang Li,et al.  Hydrophilic Fullerene Derivative Doping in Active Layer and Electron Transport Layer for Enhancing Oxygen Stability of Perovskite Solar Cells , 2020, Solar RRL.

[21]  Y. Qiu,et al.  Air stable organic salt as an n-type dopant for efficient and stable organic light-emitting diodes. , 2015, ACS applied materials & interfaces.

[22]  Z. Bao,et al.  Use of a 1H-benzoimidazole derivative as an n-type dopant and to enable air-stable solution-processed n-channel organic thin-film transistors. , 2010, Journal of the American Chemical Society.

[23]  K. Meerholz,et al.  Substrate-dependent electronic structure and film formation of MAPbI3 perovskites , 2017, Scientific Reports.

[24]  Yongfang Li,et al.  Integrating Ultrathin Bulk‐Heterojunction Organic Semiconductor Intermediary for High‐Performance Low‐Bandgap Perovskite Solar Cells with Low Energy Loss , 2018, Advanced Functional Materials.

[25]  A. Jen,et al.  In situ doping and crosslinking of fullerenes to form efficient and robust electron-transporting layers for polymer solar cells , 2014 .

[26]  Jie Zheng,et al.  Bulk heterojunction perovskite hybrid solar cells with large fill factor , 2015 .

[27]  T. Ren,et al.  Unipolar to ambipolar conversion in graphene field-effect transistors , 2012 .

[28]  T. Unold,et al.  The impact of energy alignment and interfacial recombination on the internal and external open-circuit voltage of perovskite solar cells , 2019, Energy & Environmental Science.

[29]  A. Ng,et al.  Novel Molecular Doping Mechanism for n‐Doping of SnO2 via Triphenylphosphine Oxide and Its Effect on Perovskite Solar Cells , 2019, Advanced materials.

[30]  Yaowen Li,et al.  Self‐Doping Fullerene Electrolyte‐Based Electron Transport Layer for All‐Room‐Temperature‐Processed High‐Performance Flexible Polymer Solar Cells , 2018 .

[31]  H. Snaith,et al.  Oxidative Passivation of Metal Halide Perovskites , 2019, Joule.

[32]  Z. Bao,et al.  2-(2-Methoxyphenyl)-1,3-dimethyl-1H-benzoimidazol-3-ium iodide as a new air-stable n-type dopant for vacuum-processed organic semiconductor thin films. , 2012, Journal of the American Chemical Society.

[33]  Liyuan Han,et al.  n-Type Doping and Energy States Tuning in CH3NH3Pb1–xSb2x/3I3 Perovskite Solar Cells , 2016 .

[34]  Jianbin Xu,et al.  Hybrid halide perovskite solar cell precursors: colloidal chemistry and coordination engineering behind device processing for high efficiency. , 2015, Journal of the American Chemical Society.

[35]  Yang Yang,et al.  Supersymmetric laser arrays , 2019, Nature Photonics.

[36]  Satyaprasad P. Senanayak,et al.  Understanding charge transport in lead iodide perovskite thin-film field-effect transistors , 2017, Science Advances.

[37]  Alain Goriely,et al.  Recombination Kinetics in Organic-Inorganic Perovskites: Excitons, Free Charge, and Subgap States , 2014 .

[38]  K. Wong,et al.  A pure and stable intermediate phase is key to growing aligned and vertically monolithic perovskite crystals for efficient PIN planar perovskite solar cells with high processibility and stability , 2017 .

[39]  A. Djurišić,et al.  Dopant‐Free Small‐Molecule Hole‐Transporting Material for Inverted Perovskite Solar Cells with Efficiency Exceeding 21% , 2019, Advanced materials.

[40]  Yongfang Li,et al.  Targeted Therapy for Interfacial Engineering Toward Stable and Efficient Perovskite Solar Cells , 2019, Advanced materials.

[41]  W. S. Subhani,et al.  Metal Cations in Efficient Perovskite Solar Cells: Progress and Perspective , 2019, Advanced materials.

[42]  Jinsong Huang,et al.  Imperfections and their passivation in halide perovskite solar cells. , 2019, Chemical Society reviews.

[43]  Dong Suk Kim,et al.  Methylammonium Chloride Induces Intermediate Phase Stabilization for Efficient Perovskite Solar Cells , 2019, Joule.

[44]  M. Li,et al.  N-type Doping of Organic-Inorganic Hybrid Perovskites Toward High-Performance Photovoltaic Devices , 2018, Solar RRL.

[45]  Yun Wang,et al.  A Gradient Heterostructure Based on Tolerance Factor in High‐Performance Perovskite Solar Cells with 0.84 Fill Factor , 2018, Advanced materials.

[46]  Sang Il Seok,et al.  High-performance photovoltaic perovskite layers fabricated through intramolecular exchange , 2015, Science.

[47]  Min Gyu Kim,et al.  Unveiling the relationship between the perovskite precursor solution and the resulting device performance. , 2020, Journal of the American Chemical Society.

[48]  Sang Il Seok,et al.  Solvent engineering for high-performance inorganic-organic hybrid perovskite solar cells. , 2014, Nature materials.

[49]  Wei Chen,et al.  Perovskite solar cells with 18.21% efficiency and area over 1 cm2 fabricated by heterojunction engineering , 2016, Nature Energy.

[50]  Chem. , 2020, Catalysis from A to Z.

[51]  W. Jo,et al.  Performance enhancement of planar heterojunction perovskite solar cells by n-doping of the electron transporting layer. , 2015, Chemical communications.

[52]  A. Jen,et al.  In‐situ Crosslinking and n‐Doping of Semiconducting Polymers and Their Application as Efficient Electron‐Transporting Materials in Inverted Polymer Solar Cells , 2011 .

[53]  Jun Ji,et al.  Planar p–n homojunction perovskite solar cells with efficiency exceeding 21.3% , 2019, Nature Energy.

[54]  Ruixiang Peng,et al.  Schottky/p-n Cascade Heterojunction Constructed by Intentional n-Type Doping Perovskite Toward Efficient Electron Layer-Free Perovskite Solar Cells , 2019, Solar RRL.

[55]  Alex K.-Y. Jen,et al.  Recent progress and perspective in solution-processed Interfacial materials for efficient and stable polymer and organometal perovskite solar cells , 2015 .

[56]  Tomas Leijtens,et al.  Electronic properties of meso-superstructured and planar organometal halide perovskite films: charge trapping, photodoping, and carrier mobility. , 2014, ACS nano.

[57]  Konrad Wojciechowski,et al.  Efficient and Air‐Stable Mixed‐Cation Lead Mixed‐Halide Perovskite Solar Cells with n‐Doped Organic Electron Extraction Layers , 2017, Advanced materials.

[58]  Anders Hagfeldt,et al.  Polymer-templated nucleation and crystal growth of perovskite films for solar cells with efficiency greater than 21% , 2016, Nature Energy.

[59]  Shangfeng Yang,et al.  Pyridine-functionalized fullerene additive enabling coordination interactions with CH3NH3PbI3 perovskite towards highly efficient bulk heterojunction solar cells , 2019, Journal of Materials Chemistry A.

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

[61]  Qi Chen,et al.  Reconfiguration of interfacial energy band structure for high-performance inverted structure perovskite solar cells , 2019, Nature Communications.

[62]  Bo Chen,et al.  Defect passivation in hybrid perovskite solar cells using quaternary ammonium halide anions and cations , 2017, Nature Energy.

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

[64]  G. Yu,et al.  n-Type doping for efficient polymeric electron-transporting layers in perovskite solar cells , 2016 .

[65]  Shangfeng Yang,et al.  Double fullerene cathode buffer layers afford highly efficient and stable inverted planar perovskite solar cells , 2020 .