@article{Scirè2022, 
author = {Daniele Scirè and Roberto Macaluso and Mauro Mosca and Maria Pia Casaletto and Olindo Isabella and Miro Zeman and Isodiana Crupi},
title = {Density of states characterization of TiO2 films deposited by pulsed laser deposition for heterojunction solar cells},
year = {2022},
journal = {Nano Research},
volume = {15},
number = {5},
pages = {4048-4057},
keywords = {defects, solar cell, heterojunction, photovoltaic (PV), defect density, small polaron, pulsed laser deposition (PLD), titanium dioxide (TiO2)},
url = {https://www.sciopen.com/article/10.1007/s12274-021-3985-8},
doi = {10.1007/s12274-021-3985-8},
abstract = {The application of titanium dioxide (TiO2) in the photovoltaic (PV) field is gaining traction as this material can be deployed in doping-free heterojunction solar cells with the role of electron selective contact. For modeling-based optimization of such contact, knowledge of the titanium oxide defect density of states (DOS) is crucial. In this paper, we report a method to extract the defect density through nondestructive optical measures, including the contribution given by small polaron optical transitions. The presence of both related to oxygen-vacancy defects and polarons is supported by the results of optical characterizations and the evaluation of previous observations resulting in a defect band fixed at 1 eV below the conduction band edge of the oxide. Solar cells employing pulsed laser deposited-TiO2 electron selective contacts were fabricated and characterized. The J–V curve of these cells showed, however, an S-shape, then a detailed analysis of the reasons for such behavior was carried out. We use a model involving the series of a standard cell equivalent circuit with a Schottky junction in order to explain these atypical performances. A good matching between the experimental measurements and the adopted theoretical model was obtained. The extracted parameters are listed and analyzed to shed light on the reasons behind the low-performance cells.}
}