• Q ZAFAR

Articles written in Bulletin of Materials Science

• A study of electromagnetic light propagation in a perovskite-based solar cell via a computational modelling approach

Recently, there has been huge surge of scientific interest in organic–inorganic hybrid perovskite solar cells by virtue of their high efficiency and low cost fabrication procedures. Herein, we examine the light propagation inside a planar perovskite solar cell structure (ITO/TiO$_2$/ZnO/CH$_3$NH$_3$PbI$_3$/Spiro-OMeTAD/Al) by solving the Helmholtz equation inthe finite element-frequency domain. The simulations were conducted using the COMSOL multiphysics finite element solver to carry out the two-dimensional optical modelling of simulated solar cells in the visible region. It has been observed that shorter wavelengths of light are significantly absorbed by the top region of the photoactive perovskite layer. Specifically, at a wavelength of 400 nm, the effective optical power penetration decays to zero at only 40% of the overall length of the photoactive layer. This observation has been attributed to the high absorption coefficient of the CH$_3$NH$_3$PbI$_3$ perovskitematerial at shorter wavelengths. However, at longer wavelengths, the incident light propagates deeper into the photoactive layer, reaching 100% penetration. Based on the numerical computation, a maximum generation rate of $\sim 3.43\times 10^{23}$ m$^3$ s$^{−1}$ has been observed in the photoactive layer at a wavelength of 550 nm.

• Investigation of relative humidity-sensing performance of capacitive and resistive type sensor based on TDTBPPNi metalloporphyrin dielectric layer

A quest for a suitable method to fabricate thin films-based humidity sensor with superior sensitivity in their electric response, calls for a selection of an appropriate material and effective fabrication technique. In this paper, organic semiconductor metalloporphyrin (TDTBPPNi) has been utilized to fabricate highly sensitive humidity sensors by using anovel eco-benign microwave-assisted synthetic procedure. Metalloporphyrin (TDTBPPNi) has been later deposited through facile drop-casting technique on the gap (40${\mu}$m) between planar metallic aluminium (Al) electrodes to fabricate surface-type capacitive and resistive type relative humidity sensor (Al/TDTBPPNi/Al). The structural and morphological characterizations of humidity sensing layer have been investigated, which indicate amorphous structure and rough globular surface morphology of the thin film, respectively. The relative humidity sensing capacitive and resistive characteristics of the sensor have been monitored in 39–85% relative humidity (%RH) bandwidth. The fabricated sensor under biasing condition of 1 V of applied bias ($V$$_{rms}$) and 200 Hz AC test frequency, exhibits significantly higher sensitivity of ${\sim}$102.61 pF/%RH and −333.07 kΩ/%RH in capacitive and resistive mode of operation. The average values of response and reset time of resistive sensor have been estimated to be ${\sim}$35 and ${\sim}$57 s, respectively. The reasons for this achieved sensitivity and response level have also been discussed.

• # Bulletin of Materials Science

Volume 46, 2023
All articles
Continuous Article Publishing mode

• # Dr Shanti Swarup Bhatnagar for Science and Technology

Posted on October 12, 2020

Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020