Our vision for high-throughput experimental exploration of PS thin films is summarized by the cartoons in Fig. . The full synthesis suite consists of three glove box-integrated tools with access to reactive sources of P and S (Fig. ). The tools are a reactive sputter system, a reactive rapid thermal annealing furnace (RRTP), and a simple thermal evaporator. Among them, the main deposition technique is combinatorial reactive sputtering (Fig. ), an established method to create combinatorial libraries by taking advantage of elemental composition-and growth temperature gradients across the substrate. Reactive gaseous sources of S and P are rather uncommon in sputter deposition systems. Nevertheless, the few examples available in the literature have demonstrated high versatility and high material quality. For a generic quaternary PS system M1-M2-P-S (where M1 and M2 are two different metals), a desirable outcome of sputter deposition of PSs is a combinatorial library with a gradient in the M1/M2 ratio in one direction, and in the P/S ratio in the perpendicular direction (Fig. ). A M1/M2 gradient is straightforward to obtain by appropriate orientation of the M1 and M2 targets (Fig. ). Conversely, the P/S ratio gradient is difficult to achieve if both the P and the S sources are non-directional, as for the case of H 2 S and PH 3 gases. A possible solution is to employ compound targets (a metal sulfide and a metal phosphide) rather than metallic targets. However, many of such targets are not commercially available, they have a high cost, a low deposition rate, and the target stoichiometry limits the range of compositions achievable in the final film. In our opinion, a more versatile solution to obtain P/S composition gradients is to employ a directional source for either sulfur or phosphorus, or both. Shown in Fig. ) is the combination of a non-directional PH 3 source for P, and a directional evaporation source for S. Due to the very high vapor pressure of S 8 (the standard solid-state form of sulfur) and its relatively low reactivity at low temperatures, S 8 is first evaporated at a low temperature in an effusion cell. Then, it is cracked into smaller, more reactive molecules in a separate high-temperature zone of the source. By appropriate orientation of the sulfur source, the result shown in Fig. is expected, which gives rise to the desired orthogonal gradients in composition.