Matched-pair experiments were initially conducted for the dimethylammonium and 4methoxyphenylammonium lead iodide systems by sampling the achievable compositional space uniformly, denoted strategy (a). As indicated in Table , there was no overall discrepancy between crystal formation in the presence or absence of water. For dimethylammonium, Nwet+ and Ndry+ were the same, and there was no systematic trend in the discrepant outcomes (N-+ = N+-). For 4-methoxylphenylammonium, no perovskites formed in this set of experiments.