Ellipsometric studies of CH3NH3PbI3 perovskite thin film on different underlayers and its effect on photovoltaic device performance

Measurement of optical constants of semiconducting thin films is an ongoing strive for optoelectronics and related applications. The optical constants (refractive index (n) and extinction coefficient (k)) plays a vital role in optimizing the thicknesses of different layers for improved performance in optoelectronic devices such as solar cells, photodetectors, light-emitting diodes, etc. In the present work, we measured the optical constants of methylammonium lead iodide (CH3NH3PbI3 or MAPbI(3)) deposited on five different underlying layers/substrates and estimated the error in simulated current density estimation for a device with the architecture of Glass/ITO/ TiO2/CH3NH3PbI3/Spiro-OMeTAD/Au. The optical modeling and performance analysis of this device has been done using transfer matrix method while spectroscopic ellipsometry has been used to measure the optical constants of MAPbI(3) film on five different types of underlayer stacks. A maximum error of around 10.6% has been observed when the optical constants are taken from MAPbI3 films deposited on the different underlying stacks. Additionally, experimental aspects of these films such as surface morphology, structural, and optical properties have also been studied to better understand and correlate the observed differences.

Automated summary

This study measured the optical constants of methylammonium lead iodide thin films on different underlying layers and analyzed the performance of devices using these films. The results showed that there was an error of approximately 10.6% when using the optical constants taken from films on different underlying layers.