Metal halide perovskites (MHPs) have emerged as a very high promising materials for optoelectronics and photonics, mostly due to their large absorption coefficient and excellent quantum yield of emission at room temperature, among other electro-optical properties of MHPs. The most surprising fact is that these properties are not very different from monocrystalline (or epitaxial films) direct semiconductors, even if MHPs are prepared as polycrystalline thin films by simple deposition methods, as spin-coating, inkjet printing and thermal evaporation, for example. The absorption coefficient is dependent on the material electronic structure and hence mostly intrinsic, but other electro-optical parameters, as the emission quantum yield, will depend on radiative and non-radiative recombination channels for free (and bound) excitons and carriers. In this way, slow carrier recombination in MHPs is considered the origin of the observed large charge carrier diffusion length, whose origin would the so-called "delayed luminescence" due to the existence of shallow non-quenching traps in these materials [1, 2]. In the talk a revision of recombination dynamics in MHPs will be presented. These materials have been successfully integrated in optical waveguides where stimulated emission is observed with very low thresholds both on rigid and flexible substrates [3-5]. Furthermore, perovskite-based photodetectors can be also integrated in the same platform paving the road towards wearable integrated photonics .
Finally, we will present the optical properties of MHP thin films using different organic cations alone or their mixture with methylammonium that produce multi-quantum-well structures (or 2D/3D) perovskites. This is an emerging field of work within the scientific community of perovskites, because of the higher stability of photovoltaic devices based on these 2D/3D MHPs. Moreover, quantum confinement in these structures introduces a new way to tune the optical properties, especially useful for emitting devices.
 Chirvony, V. S.; González-Carrero, S.; Suárez, I.; Galian, R. E.; Sessolo, M.; Bolink, H. J.; Martínez-Pastor, J. P.; Pérez-Prieto, J. Delayed luminescence in lead halide perovskite nanocrystals. J. Phys. Chem. C 2017, 121, 13381-13390.
 Chirvony, V. S.; Martínez-Pastor, J. P. Trap-limited dynamics of excited carriers and delayed luminescence in metal halide perovskites. J. Phys. Chem. Lett. 2018, accepted.
 I. Suárez, E. J. Juárez-Pérez, I. Mora-Seró, J. Bisquert and J. P. Martínez-Pastor, “Polymer/perovskite amplifying waveguides for active hybrid silicon photonics”,Advanced Materials 27,6157(2015).
 T. T. Ngo, I. Suarez, G. Antonicelli, D. Cortizo-Lacalle, J. P. Martinez-Pastor, A. Mateo-Alonso and I. Mora-Sero, “Enhancement of the Performance of Perovskite Solar Cells, LEDs and Light Amplifiers by Anti-Solvent Additive Deposition”, Advanced Materials 29, 1604056 (7 pp) (2017).
 I. Suarez, E. Hassanabadi, A. Maulu, N. Carlino, C. A. Maestri, M. Latifi, P. Bettotti, I. Mora-Sero and J. P. Martinez-Pastor, “Integrated Optical Amplifier-Photodetector on a Wearable Nanocellulose Substrate”, Advanced Optical Materials, 1800201 (8 pp)(2018).