Investigation of morphological degradation of P3HT:PCBM bulk heterojunction films exposed to long-term host solvent vapor

Abstract

A solvent atmosphere results in the degradation of P3HT:PCBM solar cells due to the formation of large PCBM crystallites.

Influence of Solvent Additive 1,8‐Octanedithiol on P3HT:PCBM Solar Cells

“…This hypothesis is in good agreement with the conclusion drawn from the absorption data. The P3HT lattice constants range from 1.7 to 1.8 nm in both directions, which matches values reported usually . From the full‐width‐at‐half‐maximum of the (100) Bragg peak, the corresponding crystal sizes are roughly estimated from the Scherrer equation (Table S1, Supporting Information).…”

Enhanced Photovoltaic Properties of Bulk Heterojunction Organic Photovoltaic Devices by an Addition of a Low Band Gap Conjugated Polymer

“…The absorption coefficient was calculated using the equation: $\epsilon =A·ln10/L$, where A is the absorbance and L is the film thickness [31]. The λ max and ε of P3HT were 519 nm and 5.22 $\times$ 10 5 cm −1 , respectively.…”

“…However, because of its small absorption range (below 650 nm) and edge-on crystalline structure, P3HT is known to be inefficient for electron transfer in OPVs [31,32]. Sharma et al expanded the absorption range by adding diketopyrrolopyrrole (DPP)-based conjugated small molecule sensitizers to the photoactive layer in order to enhance the PCE [20].…”

In-depth investigation of the charge extraction efficiency for thermally annealed inverted bulk-heterojunction solar cells

“…It was previously reported that prolonging the annealing time resulted in the enhancement of the vertical segregation of the PCBM phase and possibly lead to the formation of µm-sized PCBM aggregates which considerably increased the charge recombination rate. [33][34][35][36][37][38] In our case, since PCBM aggregates are not observed at the BHJ surface, maybe because of the too short annealing time, we considered an alternative approach consisting of washing the BHJ film with dichloromethane (DCM) in order to dissolve PCBM without affecting the P3HT morphology. Therefore, we expected the appearance of cavities in the film morphology Supplementary Information Figure S4).…”