Defect Tolerance and Intolerance in Metal-Halide Perovskites

Metal-halide perovskites present exceptional optoelectronic properties such as large light absorption coefficients, long free charge carrier diffusion lengths with ambipolar character. They are apparently protected by what is often described as a "defect tolerance" which has allowed to achieve, relatively quickly, highly performing devices. Nevertheless, there also exists a "defect intolerance" when it is dealt with stability. Further rationalization of the passivation strategies, especially for complex chemical systems, will be beneficial to achieve a full materials library which can be the platform for an efficient and reliable technology.