One of the main challenges for perovskite solar cell (PSCs) structures is their high sensitivity to humidity and ambient temperature, which significantly lowers the lifespan of these devices. Low stability of this devices is considered one of the principal limitations to make them commercialized. To increase the stability of the solar cell is to encapsulate the solar cell. The encapsulation is to cover the device with a non-reactive material, which prevents the penetration of ambient moisture and increases the thermal stability of the cell. If the uncoated device is exposed to continuous incident light for several hours, its structure is damaged while encapsulated device has a longer duration time. Several methods have been proposed for encapsulating a perovskite solar cell. The principal strategy of these methods involves deposition of a thin layer of polycarbonate polymer on the perovskite solar cell structure, resulting in layers of the desired structure. After fabrication and encapsulation process, the order of the various layers are FTO / bl-TiO2 / mp-TiO2 / Perovskite (CH3NH3PbI3) / Spiro-OMETAD / Au / Polycarbonate Polymer. To increase the effective stability, the glass coating is placed on the polycarbonate polymer. After acquiring sufficient adhesion between the glass coating and the polymer layer on the structure of PSCs, UV epoxy is used to seal the whole structure. Having performed the encapsulation, the samples were exposed every day to 85% constant humidity and 85°, C temperature for 10 hours and it was observed that the cell efficiency, under the mentioned conditions and after successive measurements, maintained to a high extent.

Nowadays, the use of renewable energy resources has been considered as one of the imminent issues in human life. By converting solar energy into electricity, solar cells can meet mos t of the needs of communities for domes tic and indus trial use. Meanwhile, polymer solar cells have received much attention in recent years for their acceptable performance and easy manufacturing method. Nevertheless, researchers are trying to simultaneously decrease the cos t of preparation and increase efficiency. In addition to the high efficacy of polymer solar cells, their s tability in the manufacturing process is a challenge. For decades, rapid advances in photovoltaic cells have s trongly linked the world of polymers and photovoltaic energies. Stable solar cells can be used in a variety of applications, such as space s tation equipment, solar vehicles, sensors, traffic lights, clocks and watches and more. Due to their high sensitivity to environmental factors, degradability and susceptibility to oxidation, polymer solar cells are very important in performance and s tability. Polymer solar cells with high sensitivity to environmental factors and configuration containing of degradable and oxidizing materials have attached much attention in the discussion of s tability and performance. In the present s tudy, effective properties in reducing the s tability of polymer solar cells, including semi-s table morphology, oxygen, heat, s tress, etc., will be discussed. Moreover, outs tanding methods for increasing s tability such as architectural manipulation and morphology of the active layer, reverse configuration, optimization of buffer layers, s table electrodes, molecular res tructuring of polymers and other components, etc. are reviewed and in each section, the principal researches are briefly discussed.

The present work is a detailed study of the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)  PEDOT:PSS films, were made to undergo different treatments to examine how they affected morphology, conductivity, transmittance, as well as the relative effect of the way the organic photovoltaic devices performed. This was done by using the PCPDTBT:PC71BM:SWCNTs and PCPDTBT:PC61BM mixtures. The process involves using DMSO and EG solvents for doping PEDOT:PSS and separately exposing the films to the vapour of ammonium hydroxide (NH4OH) solvent. After doping solvent was added to the PEDOT:PSS solution, , the conductivity and transmittance of PEDOT:PSS experienced a substantial increment, after which solvent treatment was performed by subjecting these films to NH4OH solvent. When devices were doped using PCPDTBT:PC71BM:SWCNTs or PCPDTBT:PC61BM with power conversion efficiency, The optimal organic photovoltaic devices achieved a 3.68%  as compared to 2.20% for pristine PV devices or 2.67% instead of 1.51%  for pristine devices, respectively. The solvent treatment played a significant part in enhancing conductivity in PEDOT:PSS films.

Single-walled carbon nano tube (SWCNT) is used as a buffer layer to improve the performance of polymer solar cells. The buffer layer is located between the active layer and the cathode electrode in the solar cell structure such as PET/ITO/PEDOT: PSS/MEH-PPV: C60 (1: 2) /SWCNT/Al. SWCNTs act as tunnels to help electron collection by cathode electrode, prevent the randomly movement of electrons, leading to the reduction of recombination at the interfaces after dissociation. By implementing this method, the short circuit current (Jsc) of fabricated solar cells increases from 20% to 40% depending on the solvent and the open circuit voltage (Voc) reduces slightly. Since the type of solvent has an important effect on the properties of fabricated solar cells, the active layer was spin coated using three different solvents which were Chlorobenzene, 1, 2-Dichlorobenzene and Toluene. The best performance was achieved for the device fabricated using Chlorobenzene. The resulted output powers using Chlorobenzene, 1, 2-Dichlorobenzene and Toluene were 10.04 mW/cm2, 7.59 mW/cm2 and 1.74 mW/cm2 respectively.