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Dopant‐Free, Amorphous–Crystalline Heterophase SnO 2 Electron Transport Bilayer Enables >20% Efficiency in Triple‐Cation Perovskite Solar Cells
Author(s) -
Lee Hock Beng,
Kumar Neetesh,
Ovhal Manoj Mayaji,
Kim Yeong Jae,
Song Young Min,
Kang JaeWook
Publication year - 2020
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202001559
Subject(s) - materials science , perovskite (structure) , amorphous solid , energy conversion efficiency , ohmic contact , bilayer , tin oxide , nanotechnology , optoelectronics , chemical engineering , layer (electronics) , crystallography , doping , chemistry , membrane , biology , engineering , genetics
Abstract Improving the ohmic contact and interfacial morphology between an electron transport layer (ETL) and perovskite film is the key to boost the efficiency of planar perovskite solar cells (PSCs). In the current work, an amorphous–crystalline heterophase tin oxide bilayer (Bi‐SnO 2 ) ETL is prepared via a low‐temperature solution process. Compared with the amorphous SnO 2 sol–gel film (SG‐SnO 2 ) or the crystalline SnO 2 nanoparticle (NP‐SnO 2 ) counterparts, the heterophase Bi‐SnO 2 ETL exhibits improved surface morphology, considerably fewer oxygen defects, and better energy band alignment with the perovskite without sacrificing the optical transmittance. The best PSC device (active area ≈ 0.09 cm 2 ) based on a Bi‐SnO 2 ETL is hysteresis‐less and achieves an outstanding power conversion efficiency of ≈20.39%, which is one of the highest efficiencies reported for SnO 2 ‐triple cation perovskite system based on green antisolvent. More fascinatingly, large‐area PSCs (active areas of ≈3.55 cm 2 ) based on the Bi‐SnO 2 ETL also achieves an extraordinarily high efficiency of ≈14.93% with negligible hysteresis. The improved device performance of the Bi‐SnO 2 ‐based PSC arises predominantly from the improved ohmic contact and suppressed bimolecular recombination at the ETL/perovskite interface. The tailored morphology and energy band structure of the Bi‐SnO 2 has enabled the scalable fabrication of highly efficient, hysteresis‐less PSCs.