Least energy solutions for Choquard equations involving vanishing potentials and exponential growth

In this paper, we consider the existence of solutions for Choquard equation of the form aligned -Δ u+V(|x|) u =[I_α *(Q(|x|)F(u))]Q(|x|)f(u), \ \ \ \ x∈ R², aligned - Δ u + V ( | x | ) u = [ I α ∗ ( Q ( | x | ) F ( u ) ) ] Q ( | x | ) f ( u ) , x ∈ R 2 , where the nonlinear term f has exponential growth, the radial potentials V,\ Q: R⁺ → R V , Q : R + → R are unbounded, singular at the origin or decaying to zero. By combining the variational methods, Trudinger-Moser inequality and some new approaches to estimate precisely the minimax level of the energy functional, we prove the existence of a nontrivial solution for the above problem under some weaker assumptions. Our study extends and improves the results of [Albuquerque-Ferreira-Severo, Milan J. Math. 89 (2021)] and [Alves-Shen, J. Differential Equations, 344 (2023)].