Niels Bohr began the path to the quantum mechanical model in 1913, but it took the additional theories of several other scientists to develop the quantum mechanical model. The combined work of Werner Heisenberg, Max Born, Pascual Jordan and Erwin Schrödinger laid the foundation for Albert Einstein's work.
The quantum mechanical model was born from a combination of theories and the work of multiple scientists. Bohr's shell model was partially replaced by the quantum mechanical model when the uncertainty principle and the spin of electrons forced scientists to look at electrons differently. Heisenberg's uncertainty principle introduced the problem of predicting where an electron would be. Schrödinger built upon Bohr's model of the atom by describing the odds of finding an electron in any given position, which helped partially reconcile Bohr's model with the uncertainty principle. Max Planck then hypothesized that the energy contained within an atom could not be continuously changing, and proposed that it must jump from one value to the next in stages or what he called quanta of energy. Einstein then famously built on this idea.