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Inclusion of ZnO‐based transparent conducting oxide (TCO) film layer into amorphous silicon/crystalline silicon (a‐Si/c‐Si) solar cell enhances its photovoltaic conversion efficiency. These findings have been confirmed here, using Afors HIT software. The simulation study is performed onto a solar cell that was originally lab prepared so as to use its measured parameters in the simulation. The ZnO‐based TCO films were electrodeposited on n‐type (100) silicon wafer and were simulated. X‐ray diffraction (XRD) pattern confirms the zinc blende nature of the TCO layer, and show that the preferred orientation of ZnO films is (002). Scanning electron microscopic (SEM) imaging confirms nano‐size nature of the ZnO based TCO film. For comparison purposes, cells with and without TCO layers are investigated by simulating photo‐current versus applied potential (J–V) plots. Values of fill factor (FF), short circuit current density (Jsc) open circuit potential (VCO) and conversion efficiency (η) are extracted. The energy band diagram, current density and charge carrier generation/recombination phenomena are in‐depth analyzed to understand the mechanism of enhancement in the hetero‐junction cell performance. Values of quantum efficiency (QE) are also simulated. The results show that the solar cell heterojunction is hypersensitive to the ZnO layer. The added value of using the ZnO‐based transparent conductive oxide (TCO) layer, in enhancing intrinsic thin layer (HIT) solar cell conversion efficiency, is assessed by critically comparing it with a control cell having no ZnO layer. © 2018 American Institute of Chemical Engineers Environ Prog, 2018 © 2018 American Institute of Chemical Engineers Environ Prog, 38:e13114, 2019

Light-emitting devices (LEDs) with higher performance, lower energy demand and minimal environmental impact are needed. With wide-band gaps and high emission efficiencies, III-V nitride semiconductors are useful for LEDs in short-wavelength regions. A multiple quantum well (MQW LED), based on InGaN/GaN, is proposed. The structure involves GaN(n)/InxGa1−xN(i)/GaN(i)/AlGaN(p)/GaN(p), where GaN(n) and GaN(p) have different dopants to formulate the junction at which electric field occurs, InxGa1−xN(i) is a 3 nm-thick intrinsic quantum well with (x) as indium mole fraction, GaN(i) is barrier intrinsic layer and AlGaN(p) is a 15 nm-thick electron blocking layer (EBL). Simulation is performed by Tcad-Silvaco. Various characteristics such as current versus voltage (I-V) plots, luminosity power, band diagram, spectrum response, radiative recombination rate and electric field effect, have been investigated. By controlling the InxGa1−xN(i) number of quantum wells and their indium mole fraction (0.18 or lower), all MQW LED characteristics including radiative recombination rate, needed current, spectral power and emitted light wavelength, are optimized. Increasing (x) value improves radiative recombination rate, spectral power and band gap with lower needed current. Devices with 6 quantum wells and x = 0.16 or 0.18 exhibit best performance. For power saving and environmental purposes, optimal mole ratio is x = 0.16.