Organo metal halide perovskite has attracted considerable attention recently due to its distinctive properties that make it especially useful in photovoltaic solar cells. In this work we demonstrate high open circuit voltage of 1.35 V using Al2O3/CH3NH3PbBr3 perovskite solar cells without a hole conductor. The contact potential difference under light measured by surface photovoltage spectroscopy of CH3NH3PbBr3 was more than twice that of CH3NH3PbI3, which results in smaller surface potential for the Al2O3/CH3NH3PbBr3 cells. Incident modulated photovoltage spectroscopy shows a longer recombination lifetime for the Al2O3/CH3NH3PbBr3 cells than for the TiO2/CH3NH3PbI3 cells or for the TiO2/CH3NH3PbBr3 cells, further supporting the high open circuit voltage. The possibility to gain high open circuit voltage even without a hole transport material in perovskite solar cells shows that the perovskite/metal oxide interface has a major effect on the open circuit voltage in perovskite based solar cells.
high_voltage_in_hole_conductor_free_organo_metal_halide_perovskite_solar_cells.pdfWe report for the first time on co-sensitization between CH3NH3PbI3 perovskite and PbS quantum dots (QDs) in a heterojunction solar cell to obtain a panchromatic response from the visible to near IR regions. Following the deposition of the sensitizers on a TiO2 film, an Au thin layer is evaporated on top as a back contact. Importantly, the CH3NH3PbI3 nanoparticles and the PbS QDs used here simultaneously play both the role of a light harvester and a hole conductor, rendering superfluous the use of an additional hole transporting material. The mesoscopic CH3NH3PbI3 (perovskite)–PbS (QD)/TiO2 heterojunction solar cell shows an impressive short circuit photocurrent (Jsc) of 24.63mA cm2, much higher than those of the individual CH3NH3PbI3 perovskite and the PbS QD solar cells. The advent of such co-sensitization mesoscopic heterojunction solar cells paves the way to extend the absorbance region of the promising low cost, high-efficiency perovskite based solar cells.
a_hybrid_lead_iodide_perovskite_and_lead_sulfide_qd_heterojunction_solar_cell_to_obtain_a_panchromatic_response.pdfOrgano-metal halide perovskites are composed of an ABX3 structure in which A represents a cation, B a divalent metal cation and X a halide. The organo-metal perovskite shows very good potential to be used as a light harvester in solar cells due to its direct band gap, large absorption coefficient, high carrier mobility and good stability. However, there is an important question in the photovoltaic field regarding the most advantageous architecture for perovskite based solar cells. Several studies showed sensitized perovskite solar cells achieving high performance, while high efficiency was also observed with the planar architecture. Consequently, it is still an open question regarding which operation mechanism and which architecture offers better results. This review describes both architectures, based on studies in the field. In the case of the sensitized structure, there are more difficulties in pore filling, naturally more recombination, and the possibility to use thicker metal oxide films. In the planar structure, thin metal oxide films are used, less recombination was observed and there are no infiltration problems. Both architectures exhibit long-range diffusion length and meet the demand for excellent coverage of the perovskite film.
organo-metal_perovskite_based_solar_cells.pdf