Lead halide perovskite is an excellent candidate for use as a light harvester in solar cells. Our work presents a depleted hole conductor free CH3NH3PbI3/TiO2 heterojunction solar cell using a thick CH3NH3PbI3 film. The CH3NH3PbI3 formed large crystals which function simultaneously as light harvesters and as hole transportmaterials. We performed capacitance voltage measurements, which show a depletion regionwhich extends to both n and p sides. The built-in field of the depletion region assists in the charge separation and suppresses the back reaction of electrons from the TiO2 film to the CH3NH3PbI3 film. This depleted hole conductor free CH3NH3PbI3/TiO2 heterojunction solar cell provides a power conversion efficiency of 8% with a current density of 18.8 mA cm2, the highest efficiency achieved to date for perovskite based solar cells without a hole conductor.
We prepared a quasi-solid electrolyte for dye-sensitized solar cells (DSSCs) that consist of ionic liquid and modified silica particles. Commercial bare silica F5 particles and modified silica F5 by NH2 and NH3+ groups were prepared, and fully characterized. The best photovoltaic performance was observed using the NH2 modified silica particles giving an open circuit voltage (Voc) of 815 mV, a short-circuit current (Jsc) of 11.23 mA cm-2, and a fill factor (FF) of 0.75 corresponding to an overall power conversion efficiency of 7.04% at 100 mW cm-2 AM 1.5. The modification of the silica particles by NH2 groups increases the Voc of DSSCs by around 60 mV compared to pure ionic liquid electrolyte based DSSCs.
Photovoltaic cells use semiconductors to convert sunlight into electrical current and are regarded as a key technology for a sustainable energy supply. Quantum dot-based solar cells have shown great potential as next generation, high performance, low-cost photovoltaics due to the outstanding optoelectronic properties of quantum dots and their multiple exciton generation (MEG) capability. This review focuses on QDs as light harvesters in solar cells, including different structures of QD-based solar cells, such as QD heterojunction solar cells, QD-Schottky solar cells, QD-sensitized solar cells and the recent development in organic-inorganic perovskite heterojunction solar cells. Mechanisms, procedures, advantages, disadvantages and the latest results obtained in the field are described. To summarize, a future perspective is offered.