Electrical characterization of lead halide perovskites for photovoltaic aplication

JORGE CARAM; NICOLÁS BUDINI; ROBERTO ARCE

Gramado

Congreso; XVI Brazilian MRS Meeting; 2017

Sociedade Brasileira de Pesquisa em Materiais

Over the last few years, a new research line onsolar cells based on hybrid organic-inorganic perovskites arose. These cellsshowed an unprecedentedincreasein their power conversion efficiency (PCE), from 3% to 21% over just 5 years [1].Methylammonium lead halide perovskites (such as CH3NH3PbX3, with X=Cl, Br, I) possess a great potential to improve the PCE due to remarkable properties: high absorption coefficients, largediffusion lengths and long lifetimesof charge carriers.In addition, the low-temperatures required for the solution-processing method makethese materials suitable for fabricating low-cost optoelectronic devices. Currently, the highest PCE are being obtained from PbI2/CH3NH3I or PbCl2/CH3NH3Iprecursor solutions, using gamma-butirolactoneor dimethylformamide as solvents [2]. The films aredeposited by spin-coating and then annealed at 100ºC under N2 atmosphere. In this work, we studied isolated perovskite films, deposited over glass substrates. We deposited several samples with different parameters, such asconcentrations of the precursor solutions, annealing temperature and humidity. Another parameter that was considered, which is relevant for perovskite deposition onto glass, was the substrate cleaning. The samples were studied by conventional optical microscopy, X-ray diffraction and transmittance measurements in the UV-visible range.Conductivity and photoconductivity measurements were also performedin thick samples due to experimental issues regarding the deposition of continuous thin films on glass. We discuss transport mechanisms and analyze the influence of the mentioned fabrication parameters on the resulting film quality.