Passivating the interface between halide perovskite and SnO2 by capsaicin to accelerate charge transfer and retard recombination

Abstract

Capsaicin is used to modify SnO2 quantum dots and then used as an electron-transfer material for perovskite solar cells. After capsaicin modification, the power conversion efficiency of the devices increases from 19.90 (± 0.47)% to 21.87 (± 0.28)% with a champion device of 22.24% (AM 1.5G, 100 mW/cm2). Transient photovoltage and photocurrent decay show that, after the capsaicin doping, the lifetime increases from 21.55 (± 1.54) to 27.63 (± 1.45) μs, while the charge extraction time reduces from 1.90 (± 0.09) to 1.67 (± 0.06) μs. Time-resolved photoluminescence and impedance spectrum studies show similar results. The accelerated charge transfer and retarded recombination are due to defect passivation. Space charge limited current study shows that, after modification, the trap density of devices is reduced from 2.24 × 1015 to 1.28 × 1015 cm−3. X-ray photoelectron spectroscopy and theoretical calculation indicate that the reduced trap density is due to the chemical interaction between carbonyl group (from capsaicin) and Sn atom, and that between carbonyl group and Pb atom.

Octylammonium Iodide Induced In‐situ Healing at “perovskite/Carbon” Interface to Achieve 85% RH‐moisture Stable, Hole‐Conductor‐Free Perovskite Solar Cells with Power Conversion Efficiency >19%

“…[ 55 ] As is shown in Figure a, a PCE of 19.42% is obtained, with V OC of 1.11 V, and FF of 74.30%.The V OC is comparable to CPSCs using spiro‐OMeTAD as HTM, [ 25,29 ] and even close to that of metal electrode‐basing devices whereas HTM (like spiro‐OMeTAD) is adopted. [ 56 ] The efficiency is comparable to that recently reported for planar CPSCs. [ 57 ] Note that such V OC is obtained in a hole‐conductor‐free device.…”

Improved Thermal Stability and Film Uniformity of Halide Perovskite by Confinement Effect brought by Polymer Chains of Polyvinyl Pyrrolidone

“…2θ ‐full width at half magnitude (2θ‐FWHM) is measured from the peak of 14.03 °, and then average crystallite size is calculated by Scherrer's formula. [ 31 ] As is depicted in Figure 3s, with doping concentration increasing, 2θ‐FWHM increases slowly at first, and then more quickly until the concentration reaches 0.2 mM. Accordingly, average crystallite size starts at 90 nm when no PVP is doped in organic salt, and decreases to 88, 78, 37, and 34 nm after 0.1, 0.2, 0.5, and 1 mM PVP is added, respectively.…”

“…Solution/Precursor Preparation: SnO 2 quantum dots (SnO 2 QDs) precursor was prepared like that described elsewhere. [31] PVP (DMF 10 mmol L −1 ) stock solution was prepared by dissolving PVP (1.1 mg) in DMF solution and then adding 100 µL PVP (DMF 10 mmol L −1 ) into the PbI 2 dissolved in the DMF and DMSO mixture solution (DMF: DMSO = 9.5:0.5 by volume ratio), the concentration of PbI 2 and PVP were 1.2 and 1 mmol L −1 respectively. Organic salt solution was prepared by dissolving FAI (60 mg), MACl (8.2 mg), and MABr (6 mg) in 1 mL IPA.…”

Polyvinyl Pyrrolidone Induced “Confinement Effect” on PbI2 and the Improvement on Crystallization and Thermal Stability of Perovskite

“…Solution / Precursor Preparation: SnO 2 quantum dots (SnO 2 QDs) precursor was prepared following the method like that described elsewhere. [39] To adjust the doping concentration of PVP in PbI 2 , PVP stock solution (dissolved in DMF) solution with concentration of 10 mmol L −1 was prepared at first. Then certain volume of stock solution, for example, 0, 50, 100, 200, and 400 μL was added into PbI 2 solution (1.2 mol L −1 , dissolved in solvent mixture between DMF and DMSO, with volume ratio of 9.5:0.5), to obtain blending concentration of 0, 0.5, 1, 2, and 4 mmol L −1 , respectively.…”