Excitonic Solar Cells: Highly Efficient PbS Quantum Dots and lead halide perovskite heterojunction solar cells
Lioz Etgar a
a The Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
Invited Speaker, Lioz Etgar, presentation 024
Publication date: 1st April 2013

 

 

Lead halide perovskites and Semiconductor quantum dots (QDs) currently attracted widespread attention for photovoltaic devices due their large absorption coefficients, high carrier mobility and the possibility of controlling their optoelectronic properties.

In this work two possibilities of hole conductor free heterojunction solar cells are presented, the lead iodide CH3NH3PbI3(perovskite)/TiO2 heterojunction solar cell and the PbS QDs/TiO2 heterojunction solar cell.

The lead iodide CH3NH3PbI3(perovskite)/TiO2 heterojunction solar cell was produced by deposition of perovskite nanoparticles from a solution of CH3NH3I and PbI2 in g-butyrolactone on a film of TiO2 (anatase) nanosheets exposing (001) facets. Importantly, the CH3NH3PbI3 nanoparticles assume here simultaneously both 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/cm2, 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/m2 intensity. At a lower light intensity of 100W/m2 a PCE of 7.3 % was measured.

The Solid state PbS QDs/TiO2 heterojunction solar cell were produced using layer-by-layer deposition of PbS QDs on a film of TiO2 (anatase) nanosheets exposing (001) facets. The TiO2 nanosheets are known for their slightly higher conduction band and their higher surface energy compared to normal anatase TiO2 nanoparticles (NPs). Importantly, the PbS QDs act here as photosensitizers and at the same time as hole conductors. The PbS QDs/TiO2 heterojunction solar cellproduces a short circuit photocurrent (Jsc) of 20.5 mA/cm2, an open circuit photovoltage (Voc) of 0.545 V and a fill factor (FF) of 0.38, corresponding to a light to electric power conversion efficiency (η) of 4.7% under AM1.5 illumination. The advent of such simple solution processed mesoscopic heterojunction solar cells paves the way to realize low cost, high-efficiency solar cells.



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