NOVELTY - Anti-reflective coating solution comprises a solvent; and a polymer comprising silicon (Si)-oxygen (O)-Si linkages; and at least one densifying element chemically incorporated into the polymer via a Si-O-X linkage, where X is at least one densifying element, at least one densifying element comprising at least one element selected from phosphorus, boron, antimony, bismuth, lead, arsenic, and its combinations.    USE - The anti-reflective coating solution is useful for producing optically transparent element (claimed); and for solar or photovoltaic (PV) cells.    ADVANTAGE - Chemically modified anti-reflective coating is provided having improved durability.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a method of producing an anti-reflective coating solution involving forming a solution of at least one alkoxy silane precursor material and a base catalyst in a solvent; reacting at least one alkoxy silane precursor material in the presence of the base catalyst to form a polymer matrix in the solvent; reducing the pH of the polymerized solution; and adding a densifier to the solvent, the densifier including a principal densifying element, the principal densifying element of the densifier being incorporated into the polymer matrix;    (2) a method of producing an optically transparent element involving dispensing the solution onto an optically transparent substrate; and curing the solution to form an anti-reflective coating on the optically transparent substrate; and    (3) an optically transparent element comprising an optically transparent substrate; and an anti-reflective coating disposed on at least one surface of the optically transparent substrate, the anti-reflective coating comprising a polymer, the polymer comprising Si-O-Si linkages; and at least one densifying element chemically incorporated into the polymer via a Si-O-X linkage, where X is at least one densifying element, at least one densifying element comprising at least one element selected from phosphorus, boron, antimony, bismuth, lead, arsenic, and its combinations.