Highly Efficient 17.6% Tin–Lead Mixed Perovskite Solar Cells Realized through Spike Structure

Abstract

Frequently observed high V loss in tin-lead mixed perovskite solar cells is considered to be one of the serious bottle-necks in spite of the high attainable Jsc due to wide wavelength photon harvesting. An amicable solution to minimize the V loss up to 0.50 V has been demonstrated by introducing an n-type interface with spike structure between the absorber and electron transport layer inspired by highly efficient Cu(In,Ga)Se solar cells. Introduction of a conduction band offset of ∼0.15 eV with a thin phenyl-C61-butyric acid methyl ester layer (∼25 nm) on the top of perovskite absorber resulted into improved V of 0.75 V leading to best power conversion efficiency of 17.6%. This enhancement is attributed to the facile charge flow at the interface owing to the reduction of interfacial traps and carrier recombination with spike structure as evidenced by time-resolved photoluminescence, nanosecond transient absorption, and electrochemical impedance spectroscopy measurements.

Energy Level Tuning of PEDOT:PSS for High Performance Tin‐Lead Mixed Perovskite Solar Cells

“…Although remarkable progress of Sn‐Pb mixed PSCs have been achieved in the last few years, the performance and reproducibility of such devices are still significantly behind the Pb‐only counterpart. The Sn‐Pb mixed PSCs usually exhibit relative low open‐circuit voltage ( V OC ) than expectation, probably due to the facile oxidation of Sn 2+ to Sn 4+ , non‐passivated defects at the interfaces, and non‐matched energy‐level of charge transport layers (CTLs) . The widely employed CTLs for inverted Sn‐Pb mixed PSCs included poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (PEDOT:PSS) as hole‐transporting layer (HTL) and [6,6]‐phenyl‐C 61 ‐butyric‐acid‐methyl‐ester (PCBM) or C 60 as electron‐transporting layers (ETLs), respectively, which are mainly inspired by the material selection for MAPbI 3 based solar cells.…”

“…The composition modification of perovskites will, however, inevitably shift the energy level and result non‐matched energy‐level at the HTL/perovskites and/or perovskite/ETL interfaces. Recently, by utilizing PCBM/C 60 bilayer spike structure as ETL, Hayase and co‐workers have reported improved V OC from 0.67 to 0.75 V for FA 0.5 MA 0.5 Sn 0.5 Pb 0.5 I 3 absorber . Jen et al have reduced the difference in energy level at perovskite/ETL interface, by replacing C 60 with an alternate fullerene variant, Indene‐C 60 bis‐adduct (ICBA), for MASn 0.5 Pb 0.5 I 3 absorber .…”

Vacuum‐Assisted Growth of Low‐Bandgap Thin Films (FA0.8MA0.2Sn0.5Pb0.5I3) for All‐Perovskite Tandem Solar Cells

“…[8][9][10] While tandem PV technologies based on market-dominant crystalline Si and CIGS bottom solar cells have recently demonstrated PCEs exceeding 28%, [6,11] all-perovskite tandem solar cells are still less advanced. [8,10,[12][13][14][15] LBG All-perovskite multijunction photovoltaics, combining a wide-bandgap (WBG) perovskite top solar cell (E G ≈1.6-1.8 eV) with a low-bandgap (LBG) perovskite bottom solar cell (E G < 1.3 eV), promise power conversion efficiencies (PCEs) >33%. To resolve these challenges, previous studies on LBG perovskite thin films addressed compositional engineering of the perovskite, strategies to improve the thin-film morphology, and routes to enhance the optical and electrical properties.…”

“…[8,10,[12][13][14][15] LBG All-perovskite multijunction photovoltaics, combining a wide-bandgap (WBG) perovskite top solar cell (E G ≈1.6-1.8 eV) with a low-bandgap (LBG) perovskite bottom solar cell (E G < 1.3 eV), promise power conversion efficiencies (PCEs) >33%. [16,17] To date, the highest reported PCE for mixed Sn-Pb perovskites with pure iodine as a halogen-MA 0.5 FA 0.5 Pb 0.5 Sn 0.5 I 3 -is 17.6%, [14,15] where MA and FA denote the organic cations of methylammonium and formamidinium, respectively. In this work, vacuum-assisted growth control (VAGC) of solution-processed LBG perovskite thin films based on mixed Sn-Pb perovskite compositions is reported.…”

“…[1][2][3] The optoelectronic properties of the perovskite materials enables power conversion efficiencies (PCEs) as high as 25.2% in singlejunction perovskite thin-film solar cells. [16,17] To date, the highest reported PCE for mixed Sn-Pb perovskites with pure iodine as a halogen-MA 0.5 FA 0.5 Pb 0.5 Sn 0.5 I 3 -is 17.6%, [14,15] where MA and FA denote the organic cations of methylammonium and formamidinium, respectively. Energy perovskite thin films are realized by careful compositional engineering, incorporating Sn at the site of Pb in multication perovskite crystal structures.…”