Exploring the electronic properties of Si-doped AlN (0001) surface with Cs adsorption layer for solar cell anode applications

Abstract The first-principles calculations are utilized to systematically investigate the adsorption behaviors of Cs on Si-doped AlN(0001) surfaces and its potential applications as anode material with low work function. Five Si substitution doping models and eight Cs adsorption surface models are established, respectively. Results show that Si atom tends to replace surface Al atom to form an n-type doping structure. Based on the most stable Si-doped surface, different Cs adsorption configurations with different adsorption sites and Cs coverage are analyzed. During Cs adsorption process, Cs acts as the electron donor and AlN surface is the electron acceptor. The large charge transfer at Cs adsorption interface induces a dipole moment pointing from Cs to AlN surface, which can effectively cut down the surface work function. Specifically, the 0.75 ML Cs-adsorbed surface shows the lowest work function of 0.62 eV, which has great potential application as the anode material of PETE devices. The findings in this work are generally applicable, which may shed new light on future exploration and development of low work function anode materials of PETE devices.