Electron Acceptor Materials Engineering in Colloidal Quantum Dot Solar Cells

Liu, Huan; Tang, Jiang; Kramer, Illan J.; Debnath, Ratan; Koleilat, Ghada I.; Wang, Xihua; Fisher, Armin; Li, Rui; Brzozowski, Lukasz; Levina, Larissa; Sargent, Edward H.

doi:10.1002/adma.201101783

Cited by 116 publications

(153 citation statements)

References 31 publications

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“…Usually a metal oxide is adopted as electron extraction contact and a high work function metal as hole extraction material 7 . Interfacial engineering to obtain efficient electrical contacts is a central effort of the field 8 .…”

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Selective contacts drive charge extraction in quantum dot solids via asymmetry in carrier transfer kinetics

et al. 2013

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Colloidal quantum dot solar cells achieve spectrally selective optical absorption in a thin layer of solution-processed, size-effect tuned, nanoparticles. The best devices built to date have relied heavily on drift-based transport due to the action of an electric field in a depletion region that extends throughout the thickness of the quantum dot layer. Here we study for the first time the behaviour of the best-performing class of colloidal quantum dot films in the absence of an electric field, by screening using an electrolyte. We find that the action of selective contacts on photovoltage sign and amplitude can be retained, implying that the contacts operate by kinetic preferences of charge transfer for either electrons or holes. We develop a theoretical model to explain these experimental findings. The work is the first to present a switch in the photovoltage in colloidal quantum dot solar cells by purposefully formed selective contacts, opening the way to new strategies in the engineering of colloidal quantum dot solar cells.

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Selective contacts drive charge extraction in quantum dot solids via asymmetry in carrier transfer kinetics

et al. 2013

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“…[4][5][6][7][8][9][10][11][12] Recent investigations focus on depleted heterojunction devices, employing a mesoscopic wide band gap semiconductor oxide such as TiO2 or ZnO as a thin spacer layer between the QDs and the conducting transparent oxide current collector. [13][14][15][16][17][18][19][20][21] Efficiencies of 5-6% were observed with these simple structures. In addition, a tandem QDs solar cell with the same structure has been demonstrated as well.…”

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Mesoscopic CH₃NH₃PbI₃/TiO₂Heterojunction Solar Cells

et al. 2012

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ABSTRACT:We report for the first time on a hole conductor-free mesoscopic lead iodide CH3NH3PbI3(perovskite)/TiO2 heterojunction solar cell, produced by deposition of perovskite nanoparticles from a solution of CH3NH3I and PbI2 in -butyrolactone on a 400nm thick film of TiO2 (anatase) nanosheets exposing (001) facets. An Au film was evaporated on top of the CH3NH3PbI3 served as a back contact. Importantly, the CH3NH3PbI3 nanoparticles act assumes here simultaneously the role of light harvester and hole conductor rendering superfluous the use of an additional hole transporting material. The simple mesoscopic CH3NH3PbI3/TiO2 heterojunction solar cell shows impressive photovoltaic performance with short circuit photocurrent (Jsc) of 16.1 mA/cm 2 , an open circuit photovoltage (Voc) of 0.631 V and a fill factor (FF) of 0.57, corresponding to a light to electric power conversion efficiency (PCE) of 5.5% under standard AM 1.5 solar light of 1000 W/m 2 intensity. At a lower light intensity of 100W/m 2 a PCE of 7.3 % was measured. The advent of such simple solution processed mesoscopic heterojunction solar cells paves the way for new advances to realize low cost, high-efficiency solar cells.

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“…This architecture has resulted in improved power conversion efficiencies, but is unable to take advantage of the bandgap tuning afforded by the CQD films because of the requirements imposed by band alignment with the wide-bandgap semiconductor. 11 Recently, an all-CQD rectifying p-n homojunction solar cell, termed the Quantum Junction (QJ), was reported, 12 consisting of both p-type and n-type CQD solids to form the p-n junction. This architecture extends the range of design opportunities for CQD photovoltaics, since the bandgap can be tuned, in a spatially varying fashion, across the lightabsorbing semiconductor layer by changing the CQD size.…”

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confidence: 99%