The paper introduces a novel class of solar cells composed entirely of inorganic nanocrystals, spin-cast from solution. These ultrathin, air-stable solar cells demonstrate power conversion efficiencies of up to 2.9% under simulated AM1.5G illumination. The devices are based on a donor-acceptor heterojunction, similar to organic solar cells, but with the advantage of improved stability and performance due to the use of nanocrystals. The study highlights the potential of this new class of photovoltaic devices for low-cost, stable power generation. Key findings include the demonstration of strong photoresponse and diode rectification, as well as the enhancement of performance through sintering, which improves carrier transport without significant doping. The solar cells exhibit robustness over time, with minimal degradation in performance after prolonged exposure to ambient conditions.The paper introduces a novel class of solar cells composed entirely of inorganic nanocrystals, spin-cast from solution. These ultrathin, air-stable solar cells demonstrate power conversion efficiencies of up to 2.9% under simulated AM1.5G illumination. The devices are based on a donor-acceptor heterojunction, similar to organic solar cells, but with the advantage of improved stability and performance due to the use of nanocrystals. The study highlights the potential of this new class of photovoltaic devices for low-cost, stable power generation. Key findings include the demonstration of strong photoresponse and diode rectification, as well as the enhancement of performance through sintering, which improves carrier transport without significant doping. The solar cells exhibit robustness over time, with minimal degradation in performance after prolonged exposure to ambient conditions.