Recent Advances of Organic Solar Cells with Optical Microcavities

Abstract

In recent decades, organic solar cells (OSCs) have drawn increasing interest due to their unique properties such as low cost, solution‐processing, flexibility, semitransparency, and nontoxicity. Due to some shortcomings of limited optical absorption in organic semiconductors as well as low carrier mobility and short exciton diffusion length, light‐trapping technologies such as surface plasmon resonance, photonic crystals, and microcavities (MCs) have been widely developed to improve device performance. Among these methods, the MC effect is liable to form and has unneglectable influences on the device efficiency. However, few reports systematically summarize the development of MC‐based OSCs. Herein, the principle of the MC effect is introduced first, and subsequently, the application and the development of MCs in single and multi‐junction OSCs are described in detail. Furthermore, in addition to the traditional MCs‐enhanced light absorption, other applications based on the MC structure in OSCs and other photo‐electronic conversion devices are also represented. Finally, the problems that need to be solved and the development directions of MC‐based OSCs in the future are outlined. It is believed that this review can provide new thinking for achieving high‐performance OSCs with optical means.

Recent Progress on Advanced Optical Structures for Emerging Photovoltaics and Photodetectors

“…The typical MC structure used in OPV applications is the Fabry–Pérot cavity (FP cavity) (Table 1d), also known as a planar parallel cavity, which has one dimension of size that is on the order of magnitude of the wavelength of light. [ 28 ] By incorporating two parallel planar metal films (i.e., mirrors of high reflectivity) and a layer sandwiched between them, light within the MC structure reflects, resonates, and oscillates between the “mirrors” and leads to controllable resonance within the device. Many theoretical and experimental studies and physical models of FP resonant cavities have been conducted, the details of which can be found in earlier reports.…”

“…Many theoretical and experimental studies and physical models of FP resonant cavities have been conducted, the details of which can be found in earlier reports. [ 28 ] Consequently, various resonance modes can be realized by controlling the thickness, composition, and cross‐section of metal films with MC structures. [ 157–160 ]…”

“…[ 18–24 ] For instance, Yang et al demonstrated an ST‐OPV having a PCE of 12% and an average visible transmittance (AVT) of 20% using a thin Au/Ag electrode and a strategy of transparent hole‐transporting frameworks. [ 25 ] Several light‐trapping methods, including the incorporation of antireflection layers, [ 26,27 ] microcavity (MC) structures, [ 28 ] distributed Bragg reflectors (DBRs) and photonic crystals (PCs), [ 29,30 ] and nanostructures, [ 31,32 ] have further optimized the light harvesting and optical responses of such devices. Shen and coworkers reviewed the use of MCs in OPVs, [ 28 ] whereas Lova et al highlighted the use of solution‐processed planar 1D PCs (organic material‐ and inorganic material‐based DBRs) with considerable application interest.…”

“…[ 25 ] Several light‐trapping methods, including the incorporation of antireflection layers, [ 26,27 ] microcavity (MC) structures, [ 28 ] distributed Bragg reflectors (DBRs) and photonic crystals (PCs), [ 29,30 ] and nanostructures, [ 31,32 ] have further optimized the light harvesting and optical responses of such devices. Shen and coworkers reviewed the use of MCs in OPVs, [ 28 ] whereas Lova et al highlighted the use of solution‐processed planar 1D PCs (organic material‐ and inorganic material‐based DBRs) with considerable application interest. [ 30 ] Figure shows many of the recent advances in OPVs and PSCs.…”

Ultrathin Nano-Absorbers in Photovoltaics: Prospects and Innovative Applications

“…Structural color filters and reflectors with much better thermal stability, a higher color gamut, and lower angle sensitivity, compared to dye-based filters, have been realized [11,12]. Additionally, several groups have demonstrated the potential of cavity-enhanced PV [5,6,[13][14][15]. It quickly became clear that this new PV architecture brings about a new degree of freedom, the light confinement, with which the cell can be adapted for specific applications [16].…”