Low-bandgap CH$3$NH$3$(Pb Sn)I$3$ (0 ≤ x ≤ 1) hybrid perovskites (e.g., ≈1.5–1.1 eV) demonstrating high surface coverage and superior optoelectronic properties have been 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$2$ V$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ s$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$) intrinsic carrier mobilities.