= Solution
Relative to conventional crystalline-silicon technology, many organic absorbers offer low-temperature thin-film processing and lightweight flexible devices, but have more strongly bound <excitons> and more disorder-limited charge transport. These are common material trends, not universal statements about every organic or inorganic device.
Relevant <semiconductor> properties include the absorption spectrum and optical gap, donor/acceptor <energy> levels and offsets, <dielectric screening> and <exciton> dissociation, electron/hole mobilities, <recombination> lifetimes, traps and morphological stability. Contacts must extract the appropriate carrier selectively. These properties determine the device quantities in
$$
\boxed{\eta=\frac{J_{\rm sc}V_{\rm oc}\,\mathrm{FF}}{P_{\rm in}}.}
$$
A favourable gap alone does not fix efficiency: current generation, <voltage> loss and fill factor must all be controlled.
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