Low-bandgap CH<sub>3sub>NH<sub>3sub>(Pb<sub>xsub>Sn<sub>1–sub><sub>xsub>)I<sub>3sub> (0 ≤ x ≤ 1) hybrid perovskites (e.g., ≈1.5–1.1 eV) demonstrating high surface coverage and superior optoelectronic properties are fabricated. State-of-the-art photovoltaic (PV) performance is reported with power conversion efficiencies approaching 10% in planar heterojunction architecture with small (<450 meV) energy loss compared to the bandgap and high (>100 cm<sup>2sup> V<sup>−1sup> s<sup>−1sup>) intrinsic carrier mobilities.