| This dissertation discusses the synthesis and characterization of solution processable photoluminescent quantum dots based upon indium phosphide, and investigations aimed at improving the stability of solution-processed perovskite solar cells.;In the first part, methods of synthesizing high quality photoluminescent quantum dots are studied, especially colloidal synthesis methods. A highly confined semiconductor nanostructure, using InGaP as the core and ZnSeS as a graded ternary outer shell was designed and synthesized through a combination of hot-injection and step-wise methods. The synthesized quantum dots were characterized by transmission electron microscopy (TEM), UV-vis absorbance spectroscopy, photoluminescence quantum efficiency (PLQE) measurements, and continuous wavelength (cw) laser-excited and time-resolved photoluminescence spectroscopy. These quantum dots exhibited high PLQE up to ∼ 90% with tunable emission color (spectral widths ranging from 57 nm to 72 nm). The PLQE dropped by less than 20% when the temperature increased from 25 to 145°C. The quantum dots exhibited continuous photoluminescent emission under both pulsed and continuous laser excitation, even at intensities that produce more than one exciton, on average, per quantum dot.;In the second part, we studied the solution processed perovskite solar cells (PSCs), focusing on improving the stability of perovskite films and prevention of hysteresis in device current-voltage characteristics. The planar heterojunction PSC was developed with a PCBM layer and a cross linker in the perovskite layer, to obtain more stable and less hysteretic devices. The device and active layer were characterized by scanning electron microscopy (SEM), X-Ray diffraction (XRD), current density-voltage (J-V) measurements, and photoluminescence lifetime measurements. The device performance and chemical stability were improved, with the power conversion efficiency (PCE) up to 13.9%. The hysteresis and formation of precipitates were suppressed by addition of a cross-linker to the perovskite layer. |
